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You are researching: Polycaprolactone (PCL)
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AUTHOR Daghrery, Arwa and Ferreira, Jessica A. and Xu, Jinping and Golafshan, Nasim and Kaigler, Darnell and Bhaduri, Sarit B. and Malda, Jos and Castilho, Miguel and Bottino, Marco C.
Title Tissue-specific melt electrowritten polymeric scaffolds for coordinated regeneration of soft and hard periodontal tissues [Abstract]
Year 2023
Journal/Proceedings Bioactive Materials
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Periodontitis is a chronic inflammatory condition that often causes serious damage to tooth-supporting tissues. The limited successful outcomes of clinically available approaches underscore the need for therapeutics that cannot only provide structural guidance to cells but can also modulate the local immune response. Here, three-dimensional melt electrowritten (i.e., poly(ε-caprolactone)) scaffolds with tissue-specific attributes were engineered to guide differentiation of human-derived periodontal ligament stem cells (hPDLSCs) and mediate macrophage polarization. The investigated tissue-specific scaffold attributes comprised fiber morphology (aligned vs. random) and highly-ordered architectures with distinct strand spacings (small 250 μm and large 500 μm). Macrophages exhibited an elongated morphology in aligned and highly-ordered scaffolds, while maintaining their round-shape on randomly-oriented fibrous scaffolds. Expressions of periostin and IL-10 were more pronounced on the aligned and highly-ordered scaffolds. While hPDLSCs on the scaffolds with 500 μm strand spacing show higher expression of osteogenic marker (Runx2) over 21 days, cells on randomly-oriented fibrous scaffolds showed upregulation of M1 markers. In an orthotopic mandibular fenestration defect model, findings revealed that the tissue-specific scaffolds (i.e., aligned fibers for periodontal ligament and highly-ordered 500 μm strand spacing fluorinated calcium phosphate [F/CaP]-coated fibers for bone) could enhance the mimicking of regeneration of natural periodontal tissues.
AUTHOR Dufour, A. and Gallostra, X. Barceló and O'Keeffe, C. and Eichholz, K. and Von Euw, S. and Garcia, O. and Kelly, D. J.
Title Integrating melt electrowriting and inkjet bioprinting for engineering structurally organized articular cartilage [Abstract]
Year 2022
Journal/Proceedings Biomaterials
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Successful cartilage engineering requires the generation of biological grafts mimicking the structure, composition and mechanical behaviour of the native tissue. Here melt electrowriting (MEW) was used to produce arrays of polymeric structures whose function was to orient the growth of cellular aggregates spontaneously generated within these structures, and to provide tensile reinforcement to the resulting tissues. Inkjet printing was used to deposit defined numbers of cells into MEW structures, which self-assembled into an organized array of spheroids within hours, ultimately generating a hybrid tissue that was hyaline-like in composition. Structurally, the engineered cartilage mimicked the histotypical organization observed in skeletally immature synovial joints. This biofabrication framework was then used to generate scaled-up (50 mm × 50 mm) cartilage implants containing over 3,500 cellular aggregates in under 15 min. After 8 weeks in culture, a 50-fold increase in the compressive stiffness of these MEW reinforced tissues were observed, while the tensile properties were still dominated by the polymer network, resulting in a composite construct demonstrating tension-compression nonlinearity mimetic of the native tissue. Helium ion microscopy further demonstrated the development of an arcading collagen network within the engineered tissue. This hybrid bioprinting strategy provides a versatile and scalable approach to engineer cartilage biomimetic grafts for biological joint resurfacing.
AUTHOR Daghrery, Arwa and Ferreira, Jessica A. and de Souza Araújo, Isaac J. and Clarkson, Brian H. and Eckert, George J. and Bhaduri, Sarit B. and Malda, Jos and Bottino, Marco C.
Title A Highly Ordered, Nanostructured Fluorinated CaP-Coated Melt Electrowritten Scaffold for Periodontal Tissue Regeneration [Abstract]
Year 2021
Journal/Proceedings Advanced Healthcare Materials
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Abstract Periodontitis is a chronic inflammatory, bacteria-triggered disorder affecting nearly half of American adults. Although some level of tissue regeneration is realized, its low success in complex cases demands superior strategies to amplify regenerative capacity. Herein, highly ordered scaffolds are engineered via Melt ElectroWriting (MEW), and the effects of strand spacing, as well as the presence of a nanostructured fluorinated calcium phosphate (F/CaP) coating on the adhesion/proliferation, and osteogenic differentiation of human-derived periodontal ligament stem cells, are investigated. Upon initial cell-scaffold interaction screening aimed at defining the most suitable design, MEW poly(ε-caprolactone) scaffolds with 500 µm strand spacing are chosen. Following an alkali treatment, scaffolds are immersed in a pre-established solution to allow for coating formation. The presence of a nanostructured F/CaP coating leads to a marked upregulation of osteogenic genes and attenuated bacterial growth. In vivo findings confirm that the F/CaP-coated scaffolds are biocompatible and lead to periodontal regeneration when implanted in a rat mandibular periodontal fenestration defect model. In aggregate, it is considered that this work can contribute to the development of personalized scaffolds capable of enabling tissue-specific differentiation of progenitor cells, and thus guide simultaneous and coordinated regeneration of soft and hard periodontal tissues, while providing antimicrobial protection.
AUTHOR Dubey, Nileshkumar and Ferreira, Jessica A. and Daghrery, Arwa and Aytac, Zeynep and Malda, Jos and Bhaduri, Sarit B. and Bottino, Marco C.
Title Highly Tunable Bioactive Fiber-Reinforced Hydrogel for Guided Bone Regeneration [Abstract]
Year 2020
Journal/Proceedings Acta Biomaterialia
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One of the most damaging pathologies that affects the health of both soft and hard tissues around the tooth is periodontitis. Clinically, periodontal tissue destruction has been managed by an integrated approach involving elimination of injured tissues followed by regenerative strategies with bone substitutes and/or barrier membranes. Regrettably, a barrier membrane with predictable mechanical integrity and multifunctional therapeutic features has yet to be established. Herein, we report a fiber-reinforced hydrogel with unprecedented tunability in terms of mechanical competence and therapeutic features by integration of highly porous poly(ε-caprolactone) fibrous mesh(es) with well-controlled 3D architecture into bioactive amorphous magnesium phosphate-laden gelatin methacryloyl hydrogels. The presence of amorphous magnesium phosphate and PCL mesh in the hydrogel can control the mechanical properties and improve the osteogenic ability, opening a tremendous opportunity in guided bone regeneration (GBR). Results demonstrate that the presence of PCL meshes fabricated via melt electrowriting can delay hydrogel degradation preventing soft tissue invasion and providing the mechanical barrier to allow time for slower migrating progenitor cells to participate in bone regeneration due to their ability to differentiate into bone-forming cells. Altogether, our approach offers a platform technology for the development of the next-generation of GBR membranes with tunable mechanical and therapeutic properties to amplify bone regeneration in compromised sites.
AUTHOR Peiffer, Quentin C. and de Ruijter, Mylène and van Duijn, Joost and Crottet, Denis and Dominic, Ernst and Malda, Jos and Castilho, Miguel
Title Melt electrowriting onto anatomically relevant biodegradable substrates: Resurfacing a diarthrodial joint [Abstract]
Year 2020
Journal/Proceedings Materials & Design
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Three-dimensional printed hydrogel constructs with well-organized melt electrowritten (MEW) fibre-reinforcing scaffolds have been demonstrated as a promising regenerative approach to treat small cartilage defects. Here, we investige how to translate the fabrication of small fibre-reinforced structures on flat surfaces to anatomically relevant structures. In particular, the accurate deposition of MEW-fibres onto curved surfaces of conductive and non-conductive regenerative biomaterials is studied. This study reveals that clinically relevant materials with low conductivities are compatible with resurfacing with organized MEW fibres. Importantly, accurate patterning on non-flat surfaces was successfully shown, provided that a constant electrical field strength and an electrical force normal to the substrate material is maintained. Furthermore, the application of resurfacing the geometry of the medial human femoral condyle is confirmed by the fabrication of a personalised osteochondral implant. The implant composed of an articular cartilage-resident chondroprogenitor cells (ACPCs)-laden hydrogel reinforced with a well-organized MEW scaffold retained its personalised shape, improved its compressive properties and supported neocartilage formation after 28 days in vitro culture. Overall, this study establishes the groundwork for translating MEW from planar and non-resorbable material substrates to anatomically relevant geometries and regenerative materials that the regenerative medicine field aims to create.
AUTHOR Daly, Andrew C. and Kelly, Daniel J.
Title Biofabrication of spatially organised tissues by directing the growth of cellular spheroids within 3D printed polymeric microchambers [Abstract]
Year 2019
Journal/Proceedings Biomaterials
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Successful tissue engineering requires the generation of human scale implants that mimic the structure, composition and mechanical properties of native tissues. Here, we report a novel biofabrication strategy that enables the engineering of structurally organised tissues by guiding the growth of cellular spheroids within arrays of 3D printed polymeric microchambers. With the goal of engineering stratified articular cartilage, inkjet bioprinting was used to deposit defined numbers of mesenchymal stromal cells (MSCs) and chondrocytes into pre-printed microchambers. These jetted cell suspensions rapidly underwent condensation within the hydrophobic microchambers, leading to the formation of organised arrays of cellular spheroids. The microchambers were also designed to provide boundary conditions to these spheroids, guiding their growth and eventual fusion, leading to the development of stratified cartilage tissue with a depth-dependant collagen fiber architecture that mimicked the structure of native articular cartilage. Furthermore, the composition and biomechanical properties of the bioprinted cartilage was also comparable to the native tissue. Using multi-tool biofabrication, we were also able to engineer anatomically accurate, human scale, osteochondral templates by printing this microchamber system on top of a hypertrophic cartilage region designed to support endochondral bone formation and then maintaining the entire construct in long-term bioreactor culture to enhance tissue development. This bioprinting strategy provides a versatile and scalable approach to engineer structurally organised cartilage tissues for joint resurfacing applications.
AUTHOR de Ruijter, Mylène and Ribeiro, Alexandre and Dokter, Inge and Castilho, Miguel and Malda, Jos
Title Simultaneous Micropatterning of Fibrous Meshes and Bioinks for the Fabrication of Living Tissue Constructs [Abstract]
Year 2018
Journal/Proceedings Advanced Healthcare Materials
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Abstract Fabrication of biomimetic tissues holds much promise for the regeneration of cells or organs that are lost or damaged due to injury or disease. To enable the generation of complex, multicellular tissues on demand, the ability to design and incorporate different materials and cell types needs to be improved. Two techniques are combined: extrusion-based bioprinting, which enables printing of cell-encapsulated hydrogels; and melt electrowriting (MEW), which enables fabrication of aligned (sub)-micrometer fibers into a single-step biofabrication process. Composite structures generated by infusion of MEW fiber structures with hydrogels have resulted in mechanically and biologically competent constructs; however, their preparation involves a two-step fabrication procedure that limits freedom of design of microfiber architectures and the use of multiple materials and cell types. How convergence of MEW and extrusion-based bioprinting allows fabrication of mechanically stable constructs with the spatial distributions of different cell types without compromising cell viability and chondrogenic differentiation of mesenchymal stromal cells is demonstrated for the first time. Moreover, this converged printing approach improves freedom of design of the MEW fibers, enabling 3D fiber deposition. This is an important step toward biofabrication of voluminous and complex hierarchical structures that can better resemble the characteristics of functional biological tissues.
AUTHOR Cunniffe, Gráinne and Gonzalez-Fernandez, Tomas and Daly, Andrew and Nelson Sathy, Binulal and Jeon, Oju and Alsberg, Eben and J. Kelly, Daniel
Title Three-Dimensional Bioprinting of Polycaprolactone Reinforced Gene Activated Bioinks for Bone Tissue Engineering [Abstract]
Year 2017
Journal/Proceedings Tissue Engineering Part A
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Regeneration of complex bone defects remains a significant clinical challenge. Multi-tool biofabrication has permitted the combination of various biomaterials to create multifaceted composites with tailorable mechanical properties and spatially controlled biological function. In this study we sought to use bioprinting to engineer nonviral gene activated constructs reinforced by polymeric micro-filaments. A gene activated bioink was developed using RGD-g-irradiated alginate and nano-hydroxyapatite (nHA) complexed to plasmid DNA (pDNA). This ink was combined with bonemarrow-derived mesenchymal stemcells (MSCs) and then co-printed with a polycaprolactone supporting mesh to provide mechanical stability to the construct. Reporter genes were first used to demonstrate successful cell transfection using this system, with sustained expression of the transgene detected over 14 days postbioprinting. Delivery of a combination of therapeutic genes encoding for bone morphogenic protein and transforming growth factor promoted robust osteogenesis of encapsulated MSCs in vitro, with enhanced levels of matrix deposition and mineralization observed following the incorporation of therapeutic pDNA. Gene activated MSC-laden constructs were then implanted subcutaneously, directly postfabrication, and were found to support superior levels of vascularization andmineralization compared to cell-free controls. These results validate the use of a gene activated bioink to impart biological functionality to three-dimensional bioprinted constructs.
AUTHOR Yao, Y. and Raymond, J. E. and Kauffmann, F. and Maekawa, S. and Sugai, J. V. and Lahann, J. and Giannobile, W. V.
Title Multicompartmental Scaffolds for Coordinated Periodontal Tissue Engineering [Abstract]
Year 2023
Journal/Proceedings Journal of Dental Research
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Successful periodontal repair and regeneration requires the coordinated responses from soft and hard tissues as well as the soft tissue–to–bone interfaces. Inspired by the hierarchical structure of native periodontal tissues, tissue engineering technology provides unique opportunities to coordinate multiple cell types into scaffolds that mimic the natural periodontal structure in vitro. In this study, we designed and fabricated highly ordered multicompartmental scaffolds by melt electrowriting, an advanced 3-dimensional (3D) printing technique. This strategy attempted to mimic the characteristic periodontal microenvironment through multicompartmental constructs comprising 3 tissue-specific regions: 1) a bone compartment with dense mesh structure, 2) a ligament compartment mimicking the highly aligned periodontal ligaments (PDLs), and 3) a transition region that bridges the bone and ligament, a critical feature that differentiates this system from mono- or bicompartmental alternatives. The multicompartmental constructs successfully achieved coordinated proliferation and differentiation of multiple cell types in vitro within short time, including both ligamentous- and bone-derived cells. Long-term 3D coculture of primary human osteoblasts and PDL fibroblasts led to a mineral gradient from calcified to uncalcified regions with PDL-like insertions within the transition region, an effect that is challenging to achieve with mono- or bicompartmental platforms. This process effectively recapitulates the key feature of interfacial tissues in periodontium. Collectively, this tissue-engineered approach offers a fundament for engineering periodontal tissue constructs with characteristic 3D microenvironments similar to native tissues. This multicompartmental 3D printing approach is also highly compatible with the design of next-generation scaffolds, with both highly adjustable compartmentalization properties and patient-specific shapes, for multitissue engineering in complex periodontal defects.
AUTHOR Freeman, Fiona E. and Pitacco, Pierluca and van Dommelen, Lieke H. A. and Nulty, Jessica and Browe, David C. and Shin, Jung-Youn and Alsberg, Eben and Kelly, Daniel J.
Title 3D bioprinting spatiotemporally defined patterns of growth factors to tightly control tissue regeneration [Abstract]
Year 2020
Journal/Proceedings Science Advances
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Therapeutic growth factor delivery typically requires supraphysiological dosages, which can cause undesirable off-target effects. The aim of this study was to 3D bioprint implants containing spatiotemporally defined patterns of growth factors optimized for coupled angiogenesis and osteogenesis. Using nanoparticle functionalized bioinks, it was possible to print implants with distinct growth factor patterns and release profiles spanning from days to weeks. The extent of angiogenesis in vivo depended on the spatial presentation of vascular endothelial growth factor (VEGF). Higher levels of vessel invasion were observed in implants containing a spatial gradient of VEGF compared to those homogenously loaded with the same total amount of protein. Printed implants containing a gradient of VEGF, coupled with spatially defined BMP-2 localization and release kinetics, accelerated large bone defect healing with little heterotopic bone formation. This demonstrates the potential of growth factor printing, a putative point of care therapy, for tightly controlled tissue regeneration.
AUTHOR Wesdorp, Marinus A. and Schwab, Andrea and Bektas, Ezgi Irem and Narcisi, Roberto and Eglin, David and Stoddart, Martin J. and Van Osch, Gerjo J. V. M. and D'Este, Matteo
Title A culture model to analyze the acute biomaterial-dependent reaction of human primary neutrophils in vitro [Abstract]
Year 2023
Journal/Proceedings Bioactive Materials
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Neutrophils play a pivotal role in orchestrating the immune system response to biomaterials, the onset and resolution of chronic inflammation, and macrophage polarization. However, the neutrophil response to biomaterials and the consequent impact on tissue engineering approaches is still scarcely understood. Here, we report an in vitro culture model that comprehensively describes the most important neutrophil functions in the light of tissue repair. We isolated human primary neutrophils from peripheral blood and exposed them to a panel of hard, soft, naturally- and synthetically-derived materials. The overall trend showed increased neutrophil survival on naturally derived constructs, together with higher oxidative burst, decreased myeloperoxidase and neutrophil elastase and decreased cytokine secretion compared to neutrophils on synthetic materials. The culture model is a step to better understand the immune modulation elicited by biomaterials. Further studies are needed to correlate the neutrophil response to tissue healing and to elucidate the mechanism triggering the cell response and their consequences in determining inflammation onset and resolution.
AUTHOR Pitacco, Pierluca and Sadowska, Joanna M. and O'Brien, Fergal J. and Kelly, Daniel J.
Title 3D bioprinting of cartilaginous templates for large bone defect healing [Abstract]
Year 2022
Journal/Proceedings Acta Biomaterialia
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Damaged or diseased bone can be treated using autografts or a range of different bone grafting biomaterials, however limitations with such approaches has motivated increased interest in developmentally inspired bone tissue engineering (BTE) strategies that seek to recapitulate the process of endochondral ossification (EO) as a means of regenerating critically sized defects. The clinical translation of such strategies will require the engineering of scaled-up, geometrically defined hypertrophic cartilage grafts that can be rapidly vascularised and remodelled into bone in mechanically challenging defect environments. The goal of this study was to 3D bioprint mechanically reinforced cartilaginous templates and to assess their capacity to regenerate critically sized femoral bone defects. Human mesenchymal stem/stromal cells (hMSCs) were incorporated into fibrin based bioinks and bioprinted into polycaprolactone (PCL) frameworks to produce mechanically reinforced constructs. Chondrogenic priming of such hMSC laden constructs was required to support robust vascularisation and graft mineralisation in vivo following their subcutaneous implantation into nude mice. With a view towards maximising their potential to support endochondral bone regeneration, we next explored different in vitro culture regimes to produce chondrogenic and early hypertrophic engineered grafts. Following their implantation into femoral bone defects within transiently immunosuppressed rats, such bioprinted constructs were rapidly remodelled into bone in vivo, with early hypertrophic constructs supporting higher levels of vascularisation and bone formation compared to the chondrogenic constructs. Such early hypertrophic bioprinted constructs also supported higher levels of vascularisation and spatially distinct patterns of new formation compared to BMP-2 loaded collagen scaffolds (here used as a positive control). In conclusion, this study demonstrates that fibrin based bioinks support chondrogenesis of hMSCs in vitro, which enables the bioprinting of mechanically reinforced hypertrophic cartilaginous templates capable of supporting large bone defect regeneration. These results support the use of 3D bioprinting as a strategy to scale-up the engineering of developmentally inspired templates for BTE. Statement of significance Despite the promise of developmentally inspired tissue engineering strategies for bone regeneration, there are still challenges that need to be addressed to enable clinical translation. This work reports the development and assessment (in vitro and in vivo) of a 3D bioprinting strategy to engineer mechanically-reinforced cartilaginous templates for large bone defect regeneration using human MSCs. Using distinct in vitro priming protocols, it was possible to generate cartilage grafts with altered phenotypes. More hypertrophic grafts, engineered in vitro using TGF-β3 and BMP-2, supported higher levels of blood vessel infiltration and accelerated bone regeneration in vivo. This study also identifies some of the advantages and disadvantages of such endochondral bone TE strategies over the direct delivery of BMP-2 from collagen-based scaffolds.
AUTHOR Hashimi, Noura Sayed Al and Soman, Soja Saghar and Govindharaj, Mano and Vijayavenkataraman, Sanjairaj
Title 3D printing of complex architected metamaterial structures by simple material extrusion for bone tissue engineering [Abstract]
Year 2022
Journal/Proceedings Materials Today Communications
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Triply periodic minimal surfaces (TPMS) are gaining popularity as scaffolds for bioapplications due to their unique structure, offering strong mechanical properties and biomorphic surfaces which enhance cell attachment and proliferation. In this work, polymer TPMS sheet lattices were printed using a well-known yet unprecedented technique of manufacturing such structures; which is material extrusion (specifically, pneumatic melt extrusion). This method offers a one step, straightforward yet reliable way to print complex porous structures while retaining design accuracy and significantly simplifying the process. Multiple primitive, gyroid and cubic structures were designed using MSLattice and Solidworks with 70% porosity and 2×2×3 unit cells. The scaffolds were printed by melt extrusion of polycaprolactone (PCL) at different parameters to establish the optimal settings. Morphological features (pore size and strut thickness) were determined using scanning electron microscopy (SEM) and the accuracy of print was determined by comparing to the design, showing high print accuracy and minimal percentage errors of less than 15% in all prints. Uniaxial compression testing was used to demonstrate the different deformation processes of the scaffolds and evaluate their mechanical properties, with primitive having the highest modulus and gyroid the highest yield strength. Finally, cell viability was quantified by alamar blue cell viability assay and visualized by SEM, displaying significant increase in cell proliferation and attachment, specifically in the primitive structure. Herein we will explain the challenges faced with design and print optimization and how we overcame them, making this work the first of its kind in material extrusion (pneumatic melt extrusion) printing of TPMS scaffolds.
AUTHOR Daskalakis, Evangelos and Huang, Boyang and Vyas, Cian and Acar, Anil A. and Liu, Fengyuan and Fallah, Ali and Cooper, Glen and Weightman, Andrew and Blunn, Gordon and Koç, Bahattin and Bartolo, Paulo
Title Bone Bricks: The Effect of Architecture and Material Composition on the Mechanical and Biological Performance of Bone Scaffolds [Abstract]
Year 2022
Journal/Proceedings ACS Omega
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Large bone loss injuries require high-performance scaffolds with an architecture and material composition resembling native bone. However, most bone scaffold studies focus on three-dimensional (3D) structures with simple rectangular or circular geometries and uniform pores, not able to recapitulate the geometric characteristics of the native tissue. This paper addresses this limitation by proposing novel anatomically designed scaffolds (bone bricks) with nonuniform pore dimensions (pore size gradients) designed based on new lay-dawn pattern strategies. The gradient design allows one to tailor the properties of the bricks and together with the incorporation of ceramic materials allows one to obtain structures with high mechanical properties (higher than reported in the literature for the same material composition) and improved biological characteristics.
AUTHOR Cao, Chuanliang and Huang, Pengren and Prasopthum, Aruna and Parsons, Andrew J. and Ai, Fanrong and Yang, Jing
Title Characterisation of bone regeneration in 3D printed ductile PCL/PEG/hydroxyapatite scaffolds with high ceramic microparticle concentrations [Abstract]
Year 2022
Journal/Proceedings Biomater. Sci.
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3D printed bioactive glass or bioceramic particle reinforced composite scaffolds for bone tissue engineering currently suffer from low particle concentration (100% breaking strain) by adding poly(ethylene glycol) which is biocompatible and FDA approved. The scaffolds require no post-printing washing to remove hazardous components. More exposure of HA microparticles on strut surfaces is enabled by incorporating higher HA concentrations. Compared to scaffolds with 72 wt% HA{,} scaffolds with higher HA content (90 wt%) enhance matrix formation but not new bone volume after 12 weeks implantation in rat calvarial defects. Histological analyses demonstrate that bone regeneration within the 3D printed scaffolds is via intramembranous ossification and starts in the central region of pores. Fibrous tissue that resembles non-union tissue within bone fractures is formed within pores that do not have new bone. The amount of blood vessels is similar between scaffolds with mainly fibrous tissue and those with more bone tissue{,} suggesting vascularization is not a deciding factor for determining the type of tissues regenerated within the pores of 3D printed scaffolds. Multinucleated immune cells are commonly present in all scaffolds surrounding the struts{,} suggesting a role of managing inflammation in bone regeneration within 3D printed scaffolds.
AUTHOR Sarti, Mattia and Parlani, Maria and Diaz-Gomez, Luis and Mikos, Antonios G. and Cerveri, Pietro and Casarin, Stefano and Dondossola, Eleonora
Title Deep Learning for Automated Analysis of Cellular and Extracellular Components of the Foreign Body Response in Multiphoton Microscopy Images [Abstract]
Year 2022
Journal/Proceedings Frontiers in Bioengineering and Biotechnology
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The Foreign body response (FBR) is a major unresolved challenge that compromises medical implant integration and function by inflammation and fibrotic encapsulation. Mice implanted with polymeric scaffolds coupled to intravital non-linear multiphoton microscopy acquisition enable multiparametric, longitudinal investigation of the FBR evolution and interference strategies. However, follow-up analyses based on visual localization and manual segmentation are extremely time-consuming, subject to human error, and do not allow for automated parameter extraction. We developed an integrated computational pipeline based on an innovative and versatile variant of the U-Net neural network to segment and quantify cellular and extracellular structures of interest, which is maintained across different objectives without impairing accuracy. This software for automatically detecting the elements of the FBR shows promise to unravel the complexity of this pathophysiological process.
AUTHOR Helaehil, Júlia Venturini and Lourenço, Carina Basqueira and Huang, Boyang and Helaehil, Luiza Venturini and de Camargo, Isaque Xavier and Chiarotto, Gabriela Bortolança and Santamaria-Jr, Milton and Bártolo, Paulo and Caetano, Guilherme Ferreira
Title In Vivo Investigation of Polymer-Ceramic PCL/HA and PCL/β-TCP 3D Composite Scaffolds and Electrical Stimulation for Bone Regeneration [Abstract]
Year 2022
Journal/Proceedings Polymers
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Critical bone defects are a major clinical challenge in reconstructive bone surgery. Polycaprolactone (PCL) mixed with bioceramics, such as hydroxyapatite (HA) and tricalcium phosphate (TCP), create composite scaffolds with improved biological recognition and bioactivity. Electrical stimulation (ES) aims to compensate the compromised endogenous electrical signals and to stimulate cell proliferation and differentiation. We investigated the effects of composite scaffolds (PCL with HA; and PCL with β-TCP) and the use of ES on critical bone defects in Wistar rats using eight experimental groups: untreated, ES, PCL, PCL/ES, HA, HA/ES, TCP, and TCP/ES. The investigation was based on histomorphometry, immunohistochemistry, and gene expression analysis. The vascular area was greater in the HA/ES group on days 30 and 60. Tissue mineralization was greater in the HA, HA/ES, and TCP groups at day 30, and TCP/ES at day 60. Bmp-2 gene expression was higher in the HA, TCP, and TCP/ES groups at day 30, and in the TCP/ES and PCL/ES groups at day 60. Runx-2, Osterix, and Osteopontin gene expression were also higher in the TCP/ES group at day 60. These results suggest that scaffolds printed with PCL and TCP, when paired with electrical therapy application, improve bone regeneration.
AUTHOR Hou, Yanhao and Wang, Weiguang and Bartolo, Paulo
Title Investigation of polycaprolactone for bone tissue engineering scaffolds: in vitro degradation and biological studies [Abstract]
Year 2022
Journal/Proceedings Materials & Design
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Polycaprolactone (PCL) is one of the most recognized polymeric materials used for bone tissue engineering scaffold fabrication. This study aims to evaluate the effects of the molecular weight (Mn) of PCL on the degradation kinematics, surface, microstructural, thermal, mechanical, and biological properties of 3D printed bone scaffolds. Surface properties were investigated considering water-in-air contact angle and nanoindentation tests, while morphological characteristics and degradation kinematics (accelerated degradation tests) were examined using scanning electron microscopy (SEM), pairing with thermal and mechanical properties monitored at each considered time point. A set of mathematical equations describing the variation of fiber diameter, porosity, mechanical properties, and weight, as a function of molecular weight and degradation time, were obtained based on the experimental results. Human adipose-derived stem cells (hADSCs) proliferation and differentiation tests were also conducted using in vitro colorimetric assay. All results indicated that molecular weight had impacts on the surface, mechanical and biological properties of PCL scaffolds, while no significant effects were observed on the degradation rate. Scaffolds with lower molecular weight presented better bio-mechanical properties. These findings provide useful information for the design of polymeric bone tissue engineering scaffolds.
AUTHOR Włodarczyk-Biegun, Małgorzata K. and Villiou, Maria and Koch, Marcus and Muth, Christina and Wang, Peixi and Ott, Jenna and del Campo, Aranzazu
Title Melt Electrowriting of Graded Porous Scaffolds to Mimic the Matrix Structure of the Human Trabecular Meshwork [Abstract]
Year 2022
Journal/Proceedings ACS Biomaterials Science & Engineering
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The permeability of the human trabecular meshwork (HTM) regulates eye pressure via a porosity gradient across its thickness modulated by stacked layers of matrix fibrils and cells. Changes in HTM porosity are associated with increases in intraocular pressure and the progress of diseases such as glaucoma. Engineered HTMs could help to understand the structure–function relation in natural tissues and lead to new regenerative solutions. Here, melt electrowriting (MEW) is explored as a biofabrication technique to produce fibrillar, porous scaffolds that mimic the multilayer, gradient structure of native HTM. Poly(caprolactone) constructs with a height of 125–500 μm and fiber diameters of 10–12 μm are printed. Scaffolds with a tensile modulus between 5.6 and 13 MPa and a static compression modulus in the range of 6–360 kPa are obtained by varying the scaffold design, that is, the density and orientation of the fibers and number of stacked layers. Primary HTM cells attach to the scaffolds, proliferate, and form a confluent layer within 8–14 days, depending on the scaffold design. High cell viability and cell morphology close to that in the native tissue are observed. The present work demonstrates the utility of MEW for reconstructing complex morphological features of natural tissues.
AUTHOR Daskalakis, Evangelos and Huang, Boyang and Vyas, Cian and Acar, Anil Ahmet and Fallah, Ali and Cooper, Glen and Weightman, Andrew and Koc, Bahattin and Blunn, Gordon and Bartolo, Paulo
Title Novel 3D Bioglass Scaffolds for Bone Tissue Regeneration [Abstract]
Year 2022
Journal/Proceedings Polymers
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The design of scaffolds with optimal biomechanical properties for load-bearing applications is an important topic of research. Most studies have addressed this problem by focusing on the material composition and not on the coupled effect between the material composition and the scaffold architecture. Polymer–bioglass scaffolds have been investigated due to the excellent bioactivity properties of bioglass, which release ions that activate osteogenesis. However, material preparation methods usually require the use of organic solvents that induce surface modifications on the bioglass particles, compromising the adhesion with the polymeric material thus compromising mechanical properties. In this paper, we used a simple melt blending approach to produce polycaprolactone/bioglass pellets to construct scaffolds with pore size gradient. The results show that the addition of bioglass particles improved the mechanical properties of the scaffolds and, due to the selected architecture, all scaffolds presented mechanical properties in the cortical bone region. Moreover, the addition of bioglass indicated a positive long-term effect on the biological performance of the scaffolds. The pore size gradient also induced a cell spreading gradient.
AUTHOR Eichholz, Kian and Freeman, Fiona and Pitacco, Pierluca and Nulty, Jessica and Ahern, Daniel and Burdis, Ross and Browe, David and Garcia, Orquidea and Hoey, David and Kelly, Daniel John
Title Scaffold microarchitecture regulates angiogenesis and the regeneration of large bone defects [Abstract]
Year 2022
Journal/Proceedings Biofabrication
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Abstract
Emerging 3D printing technologies can provide exquisite control over the external shape and internal architecture of scaffolds and tissue engineered constructs, enabling systematic studies to explore how geometric design features influence the regenerative process. Here we used fused deposition modelling (FDM) and melt electrowriting (MEW) to investigate how scaffold microarchitecture influences the healing of large bone defects. FDM was used to fabricate scaffolds with relatively large fibre diameters and low porosities, while MEW was used to fabricate scaffolds with smaller fibre diameters and higher porosities, with both scaffolds being designed to have comparable surface areas. Scaffold microarchitecture significantly influenced the healing response following implantation into critically sized femoral defects in rats, with the FDM scaffolds supporting the formation of larger bone spicules through its pores, while the MEW scaffolds supported the formation of a more round bone front during healing. After 12 weeks in vivo, both MEW and FDM scaffolds supported significantly higher levels of defect vascularisation compared to empty controls, while the MEW scaffolds supported higher levels of new bone formation. Somewhat surprisingly, this superior healing in the MEW group did not correlate with higher levels of angiogenesis, with the FDM scaffold supporting greater total vessel formation and the formation of larger vessels, while the MEW scaffold promoted the formation of a dense microvasculature with minimal evidence of larger vessels infiltrating the defect region. To conclude, the small fibre diameter, high porosity and high specific surface area of the MEW scaffold proved beneficial for osteogenesis and bone regeneration, demonstrating that changes in scaffold architecture enabled by this additive manufacturing technique can dramatically modulate angiogenesis and tissue regeneration without the need for complex exogenous growth factors. These results provide a valuable insight into the importance of 3D printed scaffold architecture when developing new bone tissue engineering strategies.
AUTHOR Hatt, Luan P. and Armiento, Angela R. and Mys, Karen and Thompson, Keith and Hildebrand, Maria and Nehrbass, Dirk and Müller, Werner E. G. and Zeiter, Stephan and Eglin, David and Stoddart, Martin J.
Title Standard in vitro evaluations of engineered bone substitutes are not sufficient to predict in vivo preclinical model outcomes [Abstract]
Year 2022
Journal/Proceedings Acta Biomaterialia
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Abstract
Understanding the optimal conditions required for bone healing can have a substantial impact to target the problem of non–unions and large bone defects. The combination of bioactive factors, regenerative progenitor cells and biomaterials to form a tissue engineered (TE) complex is a promising solution but translation to the clinic has been slow. We hypothesized the typical material testing algorithm used is insufficient and leads to materials being mischaracterized as promising. In the first part of this study, human bone marrow – derived mesenchymal stromal cells (hBM-MSCs) were embedded in three commonly used biomaterials (hyaluronic acid methacrylate, gelatin methacrylate and fibrin) and combined with relevant bioactive osteogenesis factors (dexamethasone microparticles and polyphosphate nanoparticles) to form a TE construct that underwent in vitro osteogenic differentiation for 28 days. Gene expression of relevant transcription factors and osteogenic markers, and von Kossa staining were performed. In the second and third part of this study, the same combination of TE constructs were implanted subcutaneously (cell containing) in T cell-deficient athymic Crl:NIH-Foxn1rnu rats for 8 weeks or cell free in an immunocompetent New Zealand white rabbit calvarial model for 6 weeks, respectively. Osteogenic performance was investigated via MicroCT imaging and histology staining. The in vitro study showed enhanced upregulation of relevant genes and significant mineral deposition within the three biomaterials, generally considered as a positive result. Subcutaneous implantation indicates none to minor ectopic bone formation. No enhanced calvarial bone healing was detected in implanted biomaterials compared to the empty defect. The reasons for the poor correlation of in vitro and in vivo outcomes are unclear and needs further investigation. This study highlights the discrepancy between in vitro and in vivo outcomes, demonstrating that in vitro data should be interpreted with extreme caution. In vitro models with higher complexity are necessary to increase value for translational studies. Statement of significance Preclinical testing of newly developed biomaterials is a crucial element of the development cycle. Despite this, there is still significant discrepancy between in vitro and in vivo test results. Within this study we investigate multiple combinations of materials and osteogenic stimulants and demonstrate a poor correlation between the in vitro and in vivo data. We propose rationale for why this may be the case and suggest a modified testing algorithm.
AUTHOR Zhang, Xiao and Liu, Yang and Zuo, Qiang and Wang, Qingyun and Li, Zuxi and Yan, Kai and Yuan, Tao and Zhang, Yi and Shen, Kai and Xie, Rui and Fan, Weimin
Title 3D Bioprinting of Biomimetic Bilayered Scaffold Consisting of Decellularized Extracellular Matrix and Silk Fibroin for Osteochondral Repair [Abstract]
Year 2021
Journal/Proceedings International Journal of Bioprinting; Vol 7, No 4 (2021)
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Abstract
Recently, three-dimensional (3D) bioprinting technology is becoming an appealing approach for osteochondral repair. However, it is challenging to develop a bilayered scaffold with anisotropic structural properties to mimic a native osteochondral tissue. Herein, we developed a bioink consisting of decellularized extracellular matrix and silk fibroin to print the bilayered scaffold. The bilayered scaffold mimics the natural osteochondral tissue by controlling the composition, mechanical properties, and growth factor release in each layer of the scaffold. The in vitro results show that each layer of scaffolds had a suitable mechanical strength and degradation rate. Furthermore, the scaffolds encapsulating transforming growth factor-beta (TGF-β) and bone morphogenetic protein-2 (BMP-2) can act as a controlled release system and promote directed differentiation of bone marrow-derived mesenchymal stem cells. Furthermore, the in vivo experiments suggested that the scaffolds loaded with growth factors promoted osteochondral regeneration in the rabbit knee joint model. Consequently, the biomimetic bilayered scaffold loaded with TGF-β and BMP-2 would be a promising strategy for osteochondral repair.
AUTHOR Nulty, Jessica and Freeman, Fiona E. and Browe, David C. and Burdis, Ross and Ahern, Daniel P. and Pitacco, Pierluca and Lee, Yu Bin and Alsberg, Eben and Kelly, Daniel J.
Title 3D Bioprinting of prevascularised implants for the repair of critically-sized bone defects [Abstract]
Year 2021
Journal/Proceedings Acta Biomaterialia
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Abstract
For 3D bioprinted tissues to be scaled-up to clinically relevant sizes, effective prevascularisation strategies are required to provide the necessary nutrients for normal metabolism and to remove associated waste by-products. The aim of this study was to develop a bioprinting strategy to engineer prevascularised tissues in vitro and to investigate the capacity of such constructs to enhance the vascularisation and regeneration of large bone defects in vivo. From a screen of different bioinks, a fibrin-based hydrogel was found to best support human umbilical vein endothelial cell (HUVEC) sprouting and the establishment of a microvessel network. When this bioink was combined with HUVECs and supporting human bone marrow stem/stromal cells (hBMSCs), these microvessel networks persisted in vitro. Furthermore, only bioprinted tissues containing both HUVECs and hBMSCs, that were first allowed to mature in vitro, supported robust blood vessel development in vivo. To assess the therapeutic utility of this bioprinting strategy, these bioinks were used to prevascularise 3D printed polycaprolactone (PCL) scaffolds, which were subsequently implanted into critically-sized femoral bone defects in rats. Microcomputed tomography (µCT) angiography revealed increased levels of vascularisation in vivo, which correlated with higher levels of new bone formation. Such prevascularised constructs could be used to enhance the vascularisation of a range of large tissue defects, forming the basis of multiple new bioprinted therapeutics. Statement of Significance This paper demonstrates a versatile 3D bioprinting technique to improve the vascularisation of tissue engineered constructs and further demonstrates how this method can be incorporated into a bone tissue engineering strategy to improve vascularisation in a rat femoral defect model.
AUTHOR Francesca Cestari and Mauro Petretta and Yuejiao Yang and Antonella Motta and Brunella Grigolo and Vincenzo M. Sglavo
Title 3D printing of PCL/nano-hydroxyapatite scaffolds derived from biogenic sources for bone tissue engineering [Abstract]
Year 2021
Journal/Proceedings Sustainable Materials and Technologies
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Abstract
Bioactive composites made of ∽85 wt% poly(ε-caprolactone) (PCL) and ∽15 wt% nanometric hydroxyapatite (HA) produced from biogenic sources were 3D printed by an extrusion-based process to obtain porous scaffolds suitable for bone regeneration. Three different composite formulations were considered by using HA synthesized from three distinct natural sources, which were collected as food wastes: cuttlefish bones, mussel shells and chicken eggshells. Composition and thermal properties of the materials were analysed by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and x-ray spectroscopy (XRD), while the morphological and mechanical properties of the 3D scaffolds were studied by means of electron microscopy (SEM) and compression tests. Bioactivity was tested by seeding human osteoblast cell line (MG63) onto the scaffolds which were analysed by confocal microscopy and Alamar Blue and PicoGreen® tests after 1 to 7 culture days. The elastic modulus (177–316 MPa) is found to be within the range reported for typical trabecular bones being increased by the presence of the bio-HA particles. Moreover, cells adhesion, viability and proliferation are largely promoted in the scaffolds containing nanometric HA with respect to pure PCL, the best results being revealed when mussel shell-derived HA is used. Indeed, different biological sources result in different cell proliferation rates, pointing that the biological origin has an impact on the cells-scaffold interaction. In general, the results show that PCL/bio-HA scaffolds possess improved mechanical properties and enhanced bioactivity when compared with pure PCL ones.
AUTHOR Vyas, Cian and Zhang, Jun and Øvrebø, Øystein and Huang, Boyang and Roberts, Iwan and Setty, Mohan and Allardyce, Benjamin and Haugen, Håvard and Rajkhowa, Rangam and Bartolo, Paulo
Title 3D printing of silk microparticle reinforced polycaprolactone scaffolds for tissue engineering applications [Abstract]
Year 2021
Journal/Proceedings Materials Science and Engineering: C
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Abstract
Polycaprolactone (PCL) scaffolds have been widely investigated for tissue engineering applications, however, they exhibit poor cell adhesion and mechanical properties. Subsequently, PCL composites have been produced to improve the material properties. This study utilises a natural material, Bombyx mori silk microparticles (SMP) prepared by milling silk fibre, to produce a composite to enhance the scaffolds properties. Silk is biocompatible and biodegradable with excellent mechanical properties. However, there are no studies using SMPs as a reinforcing agent in a 3D printed thermoplastic polymer scaffold. PCL/SMP (10, 20, 30 wt%) composites were prepared by melt blending. Rheological analysis showed that SMP loading increased the shear thinning and storage modulus of the material. Scaffolds were fabricated using a screw-assisted extrusion-based additive manufacturing system. Scanning electron microscopy and X-ray microtomography was used to determine scaffold morphology. The scaffolds had high interconnectivity with regular printed fibres and pore morphologies within the designed parameters. Compressive mechanical testing showed that the addition of SMP significantly improved the compressive Young's modulus of the scaffolds. The scaffolds were more hydrophobic with the inclusion of SMP which was linked to a decrease in total protein adsorption. Cell behaviour was assessed using human adipose derived mesenchymal stem cells. A cytotoxic effect was observed at higher particle loading (30 wt%) after 7 days of culture. By day 21, 10 wt% loading showed significantly higher cell metabolic activity and proliferation, high cell viability, and cell migration throughout the scaffold. Calcium mineral deposition was observed on the scaffolds during cell culture. Large calcium mineral deposits were observed at 30 wt% and smaller calcium deposits were observed at 10 wt%. This study demonstrates that SMPs incorporated into a PCL scaffold provided effective mechanical reinforcement, improved the rate of degradation, and increased cell proliferation, demonstrating potential suitability for bone tissue engineering applications.
AUTHOR Golafshan, Nasim and Willemsen, Koen and Kadumudi, Firoz Babu and Vorndran, Elke and Dolatshahi-Pirouz, Alireza and Weinans, Harrie and van der Wal, Bart C. H. and Malda, Jos and Castilho, Miguel
Title 3D-Printed Regenerative Magnesium Phosphate Implant Ensures Stability and Restoration of Hip Dysplasia [Abstract]
Year 2021
Journal/Proceedings Advanced Healthcare Materials
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Abstract
Abstract Osteoarthritis of the hip is a painful and debilitating condition commonly occurring in humans and dogs. One of the main causes that leads to hip osteoarthritis is hip dysplasia. Although the current surgical methods to correct dysplasia work satisfactorily in many circumstances, these are associated with serious complications, tissue resorption, and degeneration. In this study, a one-step fabrication of a regenerative hip implant with a patient-specific design and load-bearing properties is reported. The regenerative hip implant is fabricated based on patient imaging files and by an extrusion assisted 3D printing process using a flexible, bone-inducing biomaterial. The novel implant can be fixed with metallic screws to host bone and can be loaded up to physiological loads without signs of critical permanent deformation or failure. Moreover, after exposing the hip implant to accelerated in vitro degradation, it is confirmed that it is still able to support physiological loads even after losing ≈40% of its initial mass. In addition, the osteopromotive properties of the novel hip implant is demonstrated as shown by an increased expression of osteonectin and osteocalcin by cultured human mesenchymal stem cells after 21 days. Overall, the proposed hip implant provides an innovative regenerative and mechanically stable solution for hip dysplasia treatment.
AUTHOR Otto, I. A. and Capendale, P. E. and Garcia, J. P. and de Ruijter, M. and van Doremalen, R. F. M. and Castilho, M. and Lawson, T. and Grinstaff, M. W. and Breugem, C. C. and Kon, M. and Levato, R. and Malda, J.
Title Biofabrication of a shape-stable auricular structure for the reconstruction of ear deformities [Abstract]
Year 2021
Journal/Proceedings Materials Today Bio
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Abstract
Bioengineering of the human auricle remains a significant challenge, where the complex and unique shape, the generation of high-quality neocartilage, and shape preservation are key factors. Future regenerative medicine–based approaches for auricular cartilage reconstruction will benefit from a smart combination of various strategies. Our approach to fabrication of an ear-shaped construct uses hybrid bioprinting techniques, a recently identified progenitor cell population, previously validated biomaterials, and a smart scaffold design. Specifically, we generated a 3D-printed polycaprolactone (PCL) scaffold via fused deposition modeling, photocrosslinked a human auricular cartilage progenitor cell–laden gelatin methacryloyl (gelMA) hydrogel within the scaffold, and cultured the bioengineered structure in vitro in chondrogenic media for 30 days. Our results show that the fabrication process maintains the viability and chondrogenic phenotype of the cells, that the compressive properties of the combined PCL and gelMA hybrid auricular constructs are similar to native auricular cartilage, and that biofabricated hybrid auricular structures exhibit excellent shape fidelity compared with the 3D digital model along with deposition of cartilage-like matrix in both peripheral and central areas of the auricular structure. Our strategy affords an anatomically enhanced auricular structure with appropriate mechanical properties, ensures adequate preservation of the auricular shape during a dynamic in vitro culture period, and enables chondrogenically potent progenitor cells to produce abundant cartilage-like matrix throughout the auricular construct. The combination of smart scaffold design with 3D bioprinting and cartilage progenitor cells holds promise for the development of clinically translatable regenerative medicine strategies for auricular reconstruction.
AUTHOR Nulty, Jessica and Burdis, Ross and Kelly, Daniel J.
Title Biofabrication of Prevascularised Hypertrophic Cartilage Microtissues for Bone Tissue Engineering [Abstract]
Year 2021
Journal/Proceedings Frontiers in Bioengineering and Biotechnology
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DOI/URL DOI
Abstract
Bone tissue engineering (TE) has the potential to transform the treatment of challenging musculoskeletal pathologies. To date, clinical translation of many traditional TE strategies has been impaired by poor vascularisation of the implant. Addressing such challenges has motivated research into developmentally inspired TE strategies, whereby implants mimicking earlier stages of a tissue’s development are engineered in vitro and then implanted in vivo to fully mature into the adult tissue. The goal of this study was to engineer in vitro tissues mimicking the immediate developmental precursor to long bones, specifically a vascularised hypertrophic cartilage template, and to then assess the capacity of such a construct to support endochondral bone formation in vivo. To this end, we first developed a method for the generation of large numbers of hypertrophic cartilage microtissues using a microwell system, and encapsulated these microtissues into a fibrin-based hydrogel capable of supporting vasculogenesis by human umbilical vein endothelial cells (HUVECs). The microwells supported the formation of bone marrow derived stem/stromal cell (BMSC) aggregates and their differentiation toward a hypertrophic cartilage phenotype over 5 weeks of cultivation, as evident by the development of a matrix rich in sulphated glycosaminoglycan (sGAG), collagen types I, II, and X, and calcium. Prevascularisation of these microtissues, undertaken in vitro 1 week prior to implantation, enhanced their capacity to mineralise, with significantly higher levels of mineralised tissue observed within such implants after 4 weeks in vivo within an ectopic murine model for bone formation. It is also possible to integrate such microtissues into 3D bioprinting systems, thereby enabling the bioprinting of scaled-up, patient-specific prevascularised implants. Taken together, these results demonstrate the development of an effective strategy for prevascularising a tissue engineered construct comprised of multiple individual microtissue “building blocks,” which could potentially be used in the treatment of challenging bone defects.
AUTHOR Petretta, Mauro and Gambardella, Alessandro and Boi, Marco and Berni, Matteo and Cavallo, Carola and Marchiori, Gregorio and Maltarello, Maria Cristina and Bellucci, Devis and Fini, Milena and Baldini, Nicola and Grigolo, Brunella and Cannillo, Valeria
Title Composite Scaffolds for Bone Tissue Regeneration Based on PCL and Mg-Containing Bioactive Glasses [Abstract]
Year 2021
Journal/Proceedings Biology
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Abstract
Polycaprolactone (PCL) is widely used in additive manufacturing for the construction of scaffolds for tissue engineering because of its good bioresorbability, biocompatibility, and processability. Nevertheless, its use is limited by its inadequate mechanical support, slow degradation rate and the lack of bioactivity and ability to induce cell adhesion and, thus, bone tissue regeneration. In this study, we fabricated 3D PCL scaffolds reinforced with a novel Mg-doped bioactive glass (Mg-BG) characterized by good mechanical properties and biological reactivity. An optimization of the printing parameters and scaffold fabrication was performed; furthermore, an extensive microtopography characterization by scanning electron microscopy and atomic force microscopy was carried out. Nano-indentation tests accounted for the mechanical properties of the scaffolds, whereas SBF tests and cytotoxicity tests using human bone-marrow-derived mesenchymal stem cells (BM-MSCs) were performed to evaluate the bioactivity and in vitro viability. Our results showed that a 50/50 wt% of the polymer-to-glass ratio provides scaffolds with a dense and homogeneous distribution of Mg-BG particles at the surface and roughness twice that of pure PCL scaffolds. Compared to pure PCL (hardness H = 35 ± 2 MPa and Young’s elastic modulus E = 0.80 ± 0.05 GPa), the 50/50 wt% formulation showed H = 52 ± 11 MPa and E = 2.0 ± 0.2 GPa, hence, it was close to those of trabecular bone. The high level of biocompatibility, bioactivity, and cell adhesion encourages the use of the composite PCL/Mg-BG scaffolds in promoting cell viability and supporting mechanical loading in the host trabecular bone.
AUTHOR Bello, Thomas and Paindelli, Claudia and Diaz-Gomez, Luis A. and Melchiorri, Anthony and Mikos, Antonios G. and Nelson, Peter S. and Dondossola, Eleonora and Gujral, Taranjit S.
Title Computational modeling identifies multitargeted kinase inhibitors as effective therapies for metastatic, castration-resistant prostate cancer [Abstract]
Year 2021
Journal/Proceedings Proceedings of the National Academy of Sciences
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Abstract
Metastatic, castration-resistant prostate cancer (mCRPC) is an advanced prostate cancer with limited therapeutic options and poor patient outcomes. To investigate whether multitargeted kinase inhibitors (KIs) represent an opportunity for mCRPC drug development, we applied machine learning{textendash}based functional screening and identified two KIs, PP121 and SC-1, which demonstrated strong suppression of CRPC growth in vitro and in vivo. Furthermore, we show the marked ability of these KIs to improve on standard-of-care chemotherapy in both tumor response and survival, suggesting that combining multitargeted KIs with chemotherapy represents a promising avenue for mCRPC treatment. Overall, our findings demonstrate the application of a multidisciplinary strategy that blends bench science with machine-learning approaches for rapidly identifying KIs that result in desired phenotypic effects.Castration-resistant prostate cancer (CRPC) is an advanced subtype of prostate cancer with limited therapeutic options. Here, we applied a systems-based modeling approach called kinome regularization (KiR) to identify multitargeted kinase inhibitors (KIs) that abrogate CRPC growth. Two predicted KIs, PP121 and SC-1, suppressed CRPC growth in two-dimensional in vitro experiments and in vivo subcutaneous xenografts. An ex vivo bone mimetic environment and in vivo tibia xenografts revealed resistance to these KIs in bone. Combining PP121 or SC-1 with docetaxel, standard-of-care chemotherapy for late-stage CRPC, significantly reduced tibia tumor growth in vivo, decreased growth factor signaling, and vastly extended overall survival, compared to either docetaxel monotherapy. These results highlight the utility of computational modeling in forming physiologically relevant predictions and provide evidence for the role of multitargeted KIs as chemosensitizers for late-stage, metastatic CRPC.All study data are included in the article and/or supporting information.
AUTHOR Paindelli, Claudia and Casarin, Stefano and Wang, Feng and Diaz-Gomez, Luis and Zhang, Jianhua and Mikos, Antonios G. and Logothetis, Christopher J. and Friedl, Peter and Dondossola, Eleonora
Title Enhancing Radium 223 treatment efficacy by anti-beta 1 integrin targeting [Abstract]
Year 2021
Journal/Proceedings Journal of Nuclear Medicine
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Abstract
Radium 223 (223Ra) is an α-emitter approved for the treatment of bone metastatic prostate cancer (PCa), which exerts direct cytotoxicity towards PCa cells near the bone interface, whereas cells positioned in the core respond poorly, due to short α-particle penetrance. β1 integrin (β1I) interference has been shown to increase radiosensitivity and significantly enhance external beam radiation efficiency. We hypothesized that targeting β1I would improve 223Ra outcome. We tested the effect of combining 223Ra and anti-β1I antibody treatment in PC3 and C4-2B PCa cell models expressing high and low β1I levels, respectively. In vivo tumor growth was evaluated through bioluminescence. Cellular and molecular determinants of response were analyzed by ex vivo three-dimensional imaging of bone lesions, proteomic analysis and further confirmed by computational modeling and in vitro functional analysis in tissue-engineered bone mimetic systems. Interference with β1I combined with 223Ra reduced PC3 cell growth in bone and significantly improved overall mouse survival, while no change was achieved in C4-2B tumors. Anti-β1I treatment decreased PC3 tumor cell mitosis index and spatially expanded 223Ra lethal effects two-fold, in vivo and in silico. Regression was paralleled by decreased expression of radio-resistance mediators. Targeting β1I significantly improves 223Ra outcome and points towards combinatorial application in PCa tumors with high β1I expression.
AUTHOR Wibowo, Arie and Tajalla, Gusti U. N. and Marsudi, Maradhana A. and Cooper, Glen and Asri, Lia A.T.W. and Liu, Fengyuan and Ardy, Husaini and Bartolo, Paulo J.D.S.
Title Green Synthesis of Silver Nanoparticles Using Extract of Cilembu Sweet Potatoes (Ipomoea batatas L var. Rancing) as Potential Filler for 3D Printed Electroactive and Anti-Infection Scaffolds [Abstract]
Year 2021
Journal/Proceedings Molecules
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Abstract
Electroactive biomaterials are fascinating for tissue engineering applications because of their ability to deliver electrical stimulation directly to cells, tissue, and organs. One particularly attractive conductive filler for electroactive biomaterials is silver nanoparticles (AgNPs) because of their high conductivity, antibacterial activity, and ability to promote bone healing. However, production of AgNPs involves a toxic reducing agent which would inhibit biological scaffold performance. This work explores facile and green synthesis of AgNPs using extract of Cilembu sweet potato and studies the effect of baking and precursor concentrations (1, 10 and 100 mM) on AgNPs’ properties. Transmission electron microscope (TEM) results revealed that the smallest particle size of AgNPs (9.95 ± 3.69 nm) with nodular morphology was obtained by utilization of baked extract and ten mM AgNO3. Polycaprolactone (PCL)/AgNPs scaffolds exhibited several enhancements compared to PCL scaffolds. Compressive strength was six times greater (3.88 ± 0.42 MPa), more hydrophilic (contact angle of 76.8 ± 1.7°), conductive (2.3 ± 0.5 × 10−3 S/cm) and exhibited anti-bacterial properties against Staphylococcus aureus ATCC3658 (99.5% reduction of surviving bacteria). Despite the promising results, further investigation on biological assessment is required to obtain comprehensive study of this scaffold. This green synthesis approach together with the use of 3D printing opens a new route to manufacture AgNPs-based electroactive with improved anti-bacterial properties without utilization of any toxic organic solvents.
AUTHOR Paulo Roberto {Lopes Nalesso} and Weiguang Wang and Yanhao Hou and Leonardo Bagne and Amanda Tavares Pereira and Julia Venturini Helaehil and Thiago Antônio {Moretti de Andrade} and Gabriela Bortolança Chiarotto and Paulo Bártolo and Guilherme Ferreira Caetano
Title In vivo investigation of 3D printed polycaprolactone/graphene electro-active bone scaffolds [Abstract]
Year 2021
Journal/Proceedings Bioprinting
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Abstract
Additive manufactured scaffolds are widely used as 3D support structures for tissue engineering. This paper investigates the mechanisms behind bone regeneration due to the combined use of 3D printed poly (ϵ-caprolactone)/graphene (PCL/G) electro-active scaffolds and electrical stimulation. A comprehensive in vivo study was conducted to assess the proposed approach, using a rat model. Results show that the combined use of electro-active scaffolds and electrical stimulation therapy accelerates the bone regeneration process and the formation of more organized new bone, through fast angiogenesis, and a rapid transition to the mineralization and bone remodelling phase. The mechanism is investigated and explained.
AUTHOR e Silva, Edney P. and Huang, Boyang and Helaehil, Júlia V. and Nalesso, Paulo R. L. and Bagne, Leonardo and de Oliveira, Maraiara A. and Albiazetti, Gabriela C. C. and Aldalbahi, Ali and El-Newehy, Mohamed and Santamaria-Jr, Milton and Mendonça, Fernanda A. S. and Bártolo, Paulo and Caetano, Guilherme F.
Title In vivo study of conductive 3D printed PCL/MWCNTs scaffolds with electrical stimulation for bone tissue engineering [Abstract]
Year 2021
Journal/Proceedings Bio-Design and Manufacturing
Reftype e Silva2021
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Abstract
Critical bone defects are considered one of the major clinical challenges in reconstructive bone surgery. The combination of 3D printed conductive scaffolds and exogenous electrical stimulation (ES) is a potential favorable approach for bone tissue repair. In this study, 3D conductive scaffolds made with biocompatible and biodegradable polycaprolactone (PCL) and multi-walled carbon nanotubes (MWCNTs) were produced using the extrusion-based additive manufacturing to treat large calvary bone defects in rats. Histology results show that the use of PCL/MWCNTs scaffolds and ES contributes to thicker and increased bone tissue formation within the bone defect. Angiogenesis and mineralization are also significantly promoted using high concentration of MWCNTs (3 wt%) and ES. Moreover, scaffolds favor the tartrate-resistant acid phosphatase (TRAP) positive cell formation, while the addition of MWCNTs seems to inhibit the osteoclastogenesis but present limited effects on the osteoclast functionalities (receptor activator of nuclear factor κβ ligand (RANKL) and osteoprotegerin (OPG) expressions). The use of ES promotes the osteoclastogenesis and RANKL expressions, showing a dominant effect in the bone remodeling process. These results indicate that the combination of 3D printed conductive PCL/MWCNTs scaffold and ES is a promising strategy to treat critical bone defects and provide a cue to establish an optimal protocol to use conductive scaffolds and ES for bone tissue engineering.
AUTHOR Daskalakis, Evangelos and Liu, Fengyuan and Huang, Boyang and Acar, Anil A. and Cooper, Glen and Weightman, Andrew and Blunn, Gordon and Koç, Bahattin and Bartolo, Paulo
Title Investigating the Influence of Architecture and Material Composition of 3D Printed Anatomical Design Scaffolds for Large Bone Defects [Abstract]
Year 2021
Journal/Proceedings International Journal of Bioprinting; Vol 7, No 2 (2021)
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Abstract
There is a significant unmet clinical need to prevent amputations due to large bone loss injuries. We are addressing this problem by developing a novel, cost-effective osseointegrated prosthetic solution based on the use of modular pieces, bone bricks, made with biocompatible and biodegradable materials that fit together in a Lego-like way to form the prosthesis. This paper investigates the anatomical designed bone bricks with different architectures, pore size gradients, and material compositions. Polymer and polymer-composite 3D printed bone bricks are extensively morphological, mechanical, and biological characterized. Composite bone bricks were produced by mixing polycaprolactone (PCL) with different levels of hydroxyapatite (HA) and β-tri-calcium phosphate (TCP). Results allowed to establish a correlation between bone bricks architecture and material composition and bone bricks performance. Reinforced bone bricks showed improved mechanical and biological results. Best mechanical properties were obtained with PCL/TCP bone bricks with 38 double zig-zag filaments and 14 spiral-like pattern filaments, while the best biological results were obtained with PCL/HA bone bricks based on 25 double zig-zag filaments and 14 spiral-like pattern filaments.
AUTHOR Wang, Weiguang and Chen, Jun-Xiang and Hou, Yanhao and Bartolo, Paulo and Chiang, Wei-Hung
Title Investigations of Graphene and Nitrogen-Doped Graphene Enhanced Polycaprolactone 3D Scaffolds for Bone Tissue Engineering [Abstract]
Year 2021
Journal/Proceedings Nanomaterials
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Abstract
Scaffolds play a key role in tissue engineering applications. In the case of bone tissue engineering, scaffolds are expected to provide both sufficient mechanical properties to withstand the physiological loads, and appropriate bioactivity to stimulate cell growth. In order to further enhance cell–cell signaling and cell–material interaction, electro-active scaffolds have been developed based on the use of electrically conductive biomaterials or blending electrically conductive fillers to non-conductive biomaterials. Graphene has been widely used as functioning filler for the fabrication of electro-active bone tissue engineering scaffolds, due to its high electrical conductivity and potential to enhance both mechanical and biological properties. Nitrogen-doped graphene, a unique form of graphene-derived nanomaterials, presents significantly higher electrical conductivity than pristine graphene, and better surface hydrophilicity while maintaining a similar mechanical property. This paper investigates the synthesis and use of high-performance nitrogen-doped graphene as a functional filler of poly(ɛ-caprolactone) (PCL) scaffolds enabling to develop the next generation of electro-active scaffolds. Compared to PCL scaffolds and PCL/graphene scaffolds, these novel scaffolds present improved in vitro biological performance.
AUTHOR Petretta, Mauro and Gambardella, Alessandro and Desando, Giovanna and Cavallo, Carola and Bartolotti, Isabella and Shelyakova, Tatiana and Goranov, Vitaly and Brucale, Marco and Dediu, Valentin Alek and Fini, Milena and Grigolo, Brunella
Title Multifunctional 3D-Printed Magnetic Polycaprolactone/Hydroxyapatite Scaffolds for Bone Tissue Engineering [Abstract]
Year 2021
Journal/Proceedings Polymers
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Abstract
Multifunctional and resistant 3D structures represent a great promise and a great challenge in bone tissue engineering. This study addresses this problem by employing polycaprolactone (PCL)-based scaffolds added with hydroxyapatite (HAp) and superparamagnetic iron oxide nanoparticles (SPION), able to drive on demand the necessary cells and other bioagents for a high healing efficiency. PCL-HAp-SPION scaffolds with different concentrations of the superparamagnetic component were developed through the 3D-printing technology and the specific topographical features were detected by Atomic Force and Magnetic Force Microscopy (AFM-MFM). AFM-MFM measurements confirmed a homogenous distribution of HAp and SPION throughout the surface. The magnetically assisted seeding of cells in the scaffold resulted most efficient for the 1% SPION concentration, providing good cell entrapment and adhesion rates. Mesenchymal Stromal Cells (MSCs) seeded onto PCL-HAp-1% SPION showed a good cell proliferation and intrinsic osteogenic potential, indicating no toxic effects of the employed scaffold materials. The performed characterizations and the collected set of data point on the inherent osteogenic potential of the newly developed PCL-HAp-1% SPION scaffolds, endorsing them towards next steps of in vitro and in vivo studies and validations.
AUTHOR Salgado-Pizarro, Rebeca and Padilla, Jose Antonio and Xuriguera, Elena and Barreneche, Camila and Fernández, Ana Inés
Title Novel Shape-Stabilized Phase Change Material with Cascade Character: Synthesis, Performance and Shaping Evaluation [Abstract]
Year 2021
Journal/Proceedings Energies
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DOI/URL URL DOI
Abstract
Thermal Energy Storage (TES) materials, such as Phase Change Materials (PCMs) are proven to enhance the energy efficiency in many fields, such as automotive and building sectors, which correspond to the most energy intensive ones. Shape-stabilized PCM and cascade PCM are procedures to overcome the most important barriers when PCMs are applied since PCMs need to be encapsulated for their technical use: the leakage of the liquid phase, corrosion, low heat transfer and narrow temperature of application. In the present study, a novel shape stabilized PCM with cascade performance (cascade shape stabilized phase change material, CSS-PCM) is synthesized via dissolution, which allows up to 60 wt.% of a paraffin-PCM in the final composition. The novel CSS-PCM is based on a biopolymer, the polycaprolactone (PCL), a low melting temperature polyester as polymeric matrix and RT27 and Micronal DS 5040 acting as PCM. To evaluate the performance of the new TES materials developed, several techniques have been used: Differential Scanning Calorimetry (DSC), and Fourier-Transformed Infrared (FT-IR) spectroscopy were used to evaluate the thermophysical properties and the chemical properties of the different formulations. The CSS-PCM show an increment of storage capacity by increasing the PCM content, and the thermal reliability was also tested: some of the CSS-PCM formulations were stable for up to 500 thermal cycles. Finally, as a potential application of the new polymeric-based PCM 3D, a printing attempt was performed in order to analyze the viability of the formulations to be used as 3D printing material as a first proof of concept.
AUTHOR Korpershoek, Jasmijn V. and Ruijter, Mylène de and Terhaard, Bastiaan F. and Hagmeijer, Michella H. and Saris, Daniël B.F. and Castilho, Miguel and Malda, Jos and Vonk, Lucienne A.
Title Potential of Melt Electrowritten Scaffolds Seeded with Meniscus Cells and Mesenchymal Stromal Cells [Abstract]
Year 2021
Journal/Proceedings International Journal of Molecular Sciences
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Abstract
Meniscus injury and meniscectomy are strongly related to osteoarthritis, thus there is a clinical need for meniscus replacement. The purpose of this study is to create a meniscus scaffold with micro-scale circumferential and radial fibres suitable for a one-stage cell-based treatment. Poly-caprolactone-based scaffolds with three different architectures were made using melt electrowriting (MEW) technology and their in vitro performance was compared with scaffolds made using fused-deposition modelling (FDM) and with the clinically used Collagen Meniscus Implants® (CMI®). The scaffolds were seeded with meniscus and mesenchymal stromal cells (MSCs) in fibrin gel and cultured for 28 d. A basal level of proteoglycan production was demonstrated in MEW scaffolds, the CMI®, and fibrin gel control, yet within the FDM scaffolds less proteoglycan production was observed. Compressive properties were assessed under uniaxial confined compression after 1 and 28 d of culture. The MEW scaffolds showed a higher Young’s modulus when compared to the CMI® scaffolds and a higher yield point compared to FDM scaffolds. This study demonstrates the feasibility of creating a wedge-shaped meniscus scaffold with MEW using medical-grade materials and seeding the scaffold with a clinically-feasible cell number and -type for potential translation as a one-stage treatment.
AUTHOR Lotz, Benedict and Bothe, Friederike and Deubel, Anne-Kathrin and Hesse, Eliane and Renz, Yvonne and Werner, Carsten and Schäfer, Simone and Böck, Thomas and Groll, Jürgen and von Rechenberg, Brigitte and Richter, Wiltrud and Hagmann, Sebastien
Title Preclinical Testing of New Hydrogel Materials for Cartilage Repair: Overcoming Fixation Issues in a Large Animal Model [Abstract]
Year 2021
Journal/Proceedings International Journal of Biomaterials
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Abstract
Reinforced hydrogels represent a promising strategy for tissue engineering of articular cartilage. They can recreate mechanical and biological characteristics of native articular cartilage and promote cartilage regeneration in combination with mesenchymal stromal cells. One of the limitations of in vivo models for testing the outcome of tissue engineering approaches is implant fixation. The high mechanical stress within the knee joint, as well as the concave and convex cartilage surfaces, makes fixation of reinforced hydrogel challenging. Methods. Different fixation methods for full-thickness chondral defects in minipigs such as fibrin glue, BioGlue®, covering, and direct suturing of nonenforced and enforced constructs were compared. Because of insufficient fixation in chondral defects, superficial osteochondral defects in the femoral trochlea, as well as the femoral condyle, were examined using press-fit fixation. Two different hydrogels (starPEG and PAGE) were compared by 3D-micro-CT (μCT) analysis as well as histological analysis. Results. Our results showed fixation of below 50% for all methods in chondral defects. A superficial osteochondral defect of 1 mm depth was necessary for long-term fixation of a polycaprolactone (PCL)-reinforced hydrogel construct. Press-fit fixation seems to be adapted for a reliable fixation of 95% without confounding effects of glue or suture material. Despite the good integration of our constructs, especially in the starPEG group, visible bone lysis was detected in micro-CT analysis. There was no significant difference between the two hydrogels (starPEG and PAGE) and empty control defects regarding regeneration tissue and cell integration. However, in the starPEG group, more cell-containing hydrogel fragments were found within the defect area. Conclusion. Press-fit fixation in a superficial osteochondral defect in the medial trochlear groove of adult minipigs is a promising fixation method for reinforced hydrogels. To avoid bone lysis, future approaches should focus on multilayered constructs recreating the zonal cartilage as well as the calcified cartilage and the subchondral bone plate.
AUTHOR Hamid, Omar A. and Eltaher, Hoda M. and Sottile, Virginie and Yang, Jing
Title 3D bioprinting of a stem cell-laden, multi-material tubular composite: An approach for spinal cord repair [Abstract]
Year 2020
Journal/Proceedings Materials Science and Engineering: C
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Abstract
Development of a biomimetic tubular scaffold capable of recreating developmental neurogenesis using pluripotent stem cells offers a novel strategy for the repair of spinal cord tissues. Recent advances in 3D printing technology have facilitated biofabrication of complex biomimetic environments by precisely controlling the 3D arrangement of various acellular and cellular components (biomaterials, cells and growth factors). Here, we present a 3D printing method to fabricate a complex, patterned and embryoid body (EB)-laden tubular scaffold composed of polycaprolactone (PCL) and hydrogel (alginate or gelatine methacrylate (GelMA)). Our results revealed 3D printing of a strong, macro-porous PCL/hydrogel tubular scaffold with a high capacity to control the porosity of the PCL scaffold, wherein the maximum porosity in the PCL wall was 15%. The method was equally employed to create spatiotemporal protein concentration within the scaffold, demonstrating its ability to generate linear and opposite gradients of model molecules (fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) and rhodamine). 3D bioprinting of EBs-laden GelMA was introduced as a novel 3D printing strategy to incorporate EBs in a hydrogel matrix. Cell viability and proliferation were measured post-printing. Following the bioprinting of EBs-laden 5% GelMA hydrogel, neural differentiation of EBs was induced using 1 μM retinoic acid (RA). The differentiated EBs contained βIII-tubulin positive neurons displaying axonal extensions and cells migration. Finally, 3D bioprinting of EBs-laden PCL/GelMA tubular scaffold successfully supported EBs neural differentiation and patterning in response to co-printing with 1 μM RA. 3D printing of a complex heterogeneous tubular scaffold that can encapsulate EBs, spatially controlled protein concentration and promote neuronal patterning will help in developing more biomimetic scaffolds capable of replicating the neural patterning which occurs during neural tube development.
AUTHOR Rupp, Harald and Binder, Wolfgang H.
Title 3D Printing of Core–Shell Capsule Composites for Post-Reactive and Damage Sensing Applications [Abstract]
Year 2020
Journal/Proceedings Advanced Materials Technologies
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Abstract
Abstract 3D printing of multicomponent materials as an advantageous method over traditional mold casting methods is demonstrated, developing small core–shell capsule composites fabricated by a two-step 3D printing process. Using a two-print-head system (fused deposition modeling extruder and a liquid inkjet print head), micro-sized capsules are manufactured in sizes ranging from 100 to 800 µm. The thermoplastic polymer poly(ε-caprolactone) (PCL) is chosen as matrix/shell material due to its optimal interaction with the embedded hydrophobic liquids. First, the core–shell capsules are printed with model liquids and pure PCL to optimize the printing parameters and to ensure fully enclosed capsules inside the polymer. As a proof of concept, novel “click” reaction systems, used in self-healing and stress-detection applications, are manufactured in which PCL composites with nano- and micro-fillers are combined with reactive, encapsulated liquids. The so generated 3D printed core–shell capsule composite can be used for post-printing reactions and damage sensing when combined with a fluorogenic dye.
AUTHOR Critchley, Susan and Sheehy, Eamon J. and Cunniffe, Gráinne and Diaz-Payno, Pedro and Carroll, Simon F. and Jeon, Oju and Alsberg, Eben and Brama, Pieter A. J. and Kelly, Daniel J.
Title 3D printing of fibre-reinforced cartilaginous templates for the regeneration of osteochondral defects [Abstract]
Year 2020
Journal/Proceedings Acta Biomaterialia
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Abstract
Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage that is resistant to vascularization and endochondral ossification. During skeletal development articular cartilage also functions as a surface growth plate, which postnatally is replaced by a more spatially complex bone-cartilage interface. Motivated by this developmental process, the hypothesis of this study is that bi-phasic, fibre-reinforced cartilaginous templates can regenerate both the articular cartilage and subchondral bone within osteochondral defects created in caprine joints. To engineer mechanically competent implants, we first compared a range of 3D printed fibre networks (PCL, PLA and PLGA) for their capacity to mechanically reinforce alginate hydrogels whilst simultaneously supporting mesenchymal stem cell (MSC) chondrogenesis in vitro. These mechanically reinforced, MSC-laden alginate hydrogels were then used to engineer the endochondral bone forming phase of bi-phasic osteochondral constructs, with the overlying chondral phase consisting of cartilage tissue engineered using a co-culture of infrapatellar fat pad derived stem/stromal cells (FPSCs) and chondrocytes. Following chondrogenic priming and subcutaneous implantation in nude mice, these bi-phasic cartilaginous constructs were found to support the development of vascularised endochondral bone overlaid by phenotypically stable cartilage. These fibre-reinforced, bi-phasic cartilaginous templates were then evaluated in clinically relevant, large animal (caprine) model of osteochondral defect repair. Although the quality of repair was variable from animal-to-animal, in general more hyaline-like cartilage repair was observed after 6 months in animals treated with bi-phasic constructs compared to animals treated with commercial control scaffolds. This variability in the quality of repair points to the need for further improvements in the design of 3D bioprinted implants for joint regeneration. Statement of Significance Successful osteochondral defect repair requires regenerating the subchondral bone whilst simultaneously promoting the development of an overlying layer of articular cartilage. In this study, we hypothesised that bi-phasic, fibre-reinforced cartilaginous templates could be leveraged to regenerate both the articular cartilage and subchondral bone within osteochondral defects. To this end we used 3D printed fibre networks to mechanically reinforce engineered transient cartilage, which also contained an overlying layer of phenotypically stable cartilage engineered using a co-culture of chondrocytes and stem cells. When chondrogenically primed and implanted into caprine osteochondral defects, these fibre-reinforced bi-phasic cartilaginous grafts were shown to spatially direct tissue development during joint repair. Such developmentally inspired tissue engineering strategies, enabled by advances in biofabrication and 3D printing, could form the basis of new classes of regenerative implants in orthopaedic medicine.
AUTHOR Wibowo, Arie and Vyas, Cian and Cooper, Glen and Qulub, Fitriyatul and Suratman, Rochim and Mahyuddin, Andi Isra and Dirgantara, Tatacipta and Bartolo, Paulo
Title 3D Printing of Polycaprolactone-Polyaniline Electroactive Scaffolds for Bone Tissue Engineering. [Abstract]
Year 2020
Journal/Proceedings Materials
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Abstract
Electrostimulation and electroactive scaffolds can positively influence and guide cellular behaviour and thus has been garnering interest as a key tissue engineering strategy. The development of conducting polymers such as polyaniline enables the fabrication of conductive polymeric composite scaffolds. In this study, we report on the initial development of a polycaprolactone scaffold incorporating different weight loadings of a polyaniline microparticle filler. The scaffolds are fabricated using screw-assisted extrusion-based 3D printing and are characterised for their morphological, mechanical, conductivity, and preliminary biological properties. The conductivity of the polycaprolactone scaffolds increases with the inclusion of polyaniline. The in vitro cytocompatibility of the scaffolds was assessed using human adipose-derived stem cells to determine cell viability and proliferation up to 21 days. A cytotoxicity threshold was reached at 1% wt. polyaniline loading. Scaffolds with 0.1% wt. polyaniline showed suitable compressive strength (6.45 ± 0.16 MPa) and conductivity (2.46 ± 0.65 × 10(-4) S/cm) for bone tissue engineering applications and demonstrated the highest cell viability at day 1 (88%) with cytocompatibility for up to 21 days in cell culture.
AUTHOR Zamani, Yasaman and Amoabediny, Ghassem and Mohammadi, Javad and Seddiqi, Hadi and Helder, Marco N. and Zandieh-Doulabi, Behrouz and Klein-Nulend, Jenneke and Koolstra, Jan Harm
Title 3D-printed poly(Ɛ-caprolactone) scaffold with gradient mechanical properties according to force distribution in the mandible for mandibular bone tissue engineering [Abstract]
Year 2020
Journal/Proceedings Journal of the Mechanical Behavior of Biomedical Materials
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Abstract
In bone tissue engineering, prediction of forces induced to the native bone during normal functioning is important in the design, fabrication, and integration of a scaffold with the host. The aim of this study was to customize the mechanical properties of a layer-by-layer 3D-printed poly(ϵ-caprolactone) (PCL) scaffold estimated by finite element (FE) modeling in order to match the requirements of the defect, to prevent mechanical failure, and ensure optimal integration with the surrounding tissue. Forces and torques induced on the mandibular symphysis during jaw opening and closing were predicted by FE modeling. Based on the predicted forces, homogeneous-structured PCL scaffolds with 3 different void sizes (0.3, 0.6, and 0.9 mm) were designed and 3D-printed using an extrusion based 3D-bioprinter. In addition, 2 gradient-structured scaffolds were designed and 3D-printed. The first gradient scaffold contained 2 regions (0.3 mm and 0.6 mm void size in the upper and lower half, respectively), whereas the second gradient scaffold contained 3 regions (void sizes of 0.3, 0.6, and 0.9 mm in the upper, middle and lower third, respectively). Scaffolds were tested for their compressive and tensile strength in the upper and lower halves. The actual void size of the homogeneous scaffolds with designed void size of 0.3, 0.6, and 0.9 mm was 0.20, 0.59, and 0.95 mm, respectively. FE modeling showed that during opening and closing of the jaw, the highest force induced on the symphysis was a compressive force in the transverse direction. The compressive force was induced throughout the symphyseal line and reduced from top (362.5 N, compressive force) to bottom (107.5 N, tensile force) of the symphysis. Compressive and tensile strength of homogeneous scaffolds decreased by 1.4-fold to 3-fold with increasing scaffold void size. Both gradient scaffolds had higher compressive strength in the upper half (2 region-gradient scaffold: 4.9 MPa; 3 region-gradient scaffold: 4.1 MPa) compared with the lower half (2 region-gradient scaffold: 2.5 MPa; 3 region-gradient scaffold: 2.7 MPa) of the scaffold. 3D-printed PCL scaffolds had higher compressive strength in the scaffold layer-by-layer building direction compared with the side direction, and a very low tensile strength in the scaffold layer-by-layer building direction. Fluid shear stress and fluid pressure distribution in the gradient scaffolds were more homogeneous than in the 0.3 mm void size scaffold and similar to the 0.6 mm and 0.9 mm void size scaffolds. In conclusion, these data show that the mechanical properties of 3D-printed PCL scaffolds can be tailored based on the predicted forces on the mandibular symphysis. These 3D-printed PCL scaffolds had different mechanical properties in scaffold building direction compared with the side direction, which should be taken into account when placing the scaffold in the defect site. Our findings might have implications for improved performance and integration of scaffolds with native tissue.
AUTHOR Mancini, I. A. D. and Schmidt, S. and Brommer, H. and Pouran, B. and Schäfer, S. and Tessmar, J. and Mensinga, A. and van Rijen, M. H. P. and Groll, J. and Blunk, T. and Levato, R. and Malda, J. and van Weeren, P. R.
Title A composite hydrogel-3D printed thermoplast osteochondral anchor as example for a zonal approach to cartilage repair: in vivo performance in a long-term equine model [Abstract]
Year 2020
Journal/Proceedings Biofabrication
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Abstract
Recent research has been focusing on the generation of living personalized osteochondral constructs for joint repair. Native articular cartilage has a zonal structure, which is not reflected in current constructs and which may be a cause of the frequent failure of these repair attempts. Therefore, we investigated the performance of a composite implant that further reflects the zonal distribution of cellular component both in vitro and in vivo in a long-term equine model. Constructs constituted of a 3D-printed poly(ϵ-caprolactone) (PCL) bone anchor from which reinforcing fibers protruded into the chondral part of the construct over which two layers of a thiol-ene cross-linkable hyaluronic acid/poly(glycidol) hybrid hydrogel (HA-SH/P(AGE-co-G)) were fabricated. The top layer contained Articular Cartilage Progenitor Cells (ACPCs) derived from the superficial layer of native cartilage tissue, the bottom layer contained mesenchymal stromal cells (MSCs). The chondral part of control constructs were homogeneously filled with MSCs. After six months in vivo, microtomography revealed significant bone growth into the anchor. Histologically, there was only limited production of cartilage-like tissue (despite persistency of hydrogel) both in zonal and non-zonal constructs. There were no differences in histological scoring; however, the repair tissue was significantly stiffer in defects repaired with zonal constructs. The sub-optimal quality of the repair tissue may be related to several factors, including early loss of implanted cells, or inappropriate degradation rate of the hydrogel. Nonetheless, this approach may be promising and research into further tailoring of biomaterials and of construct characteristics seems warranted.
AUTHOR Huang, Boyang and Vyas, Cian and Byun, Jae Jong and El-Newehy, Mohamed and Huang, Zhucheng and Bártolo, Paulo
Title Aligned multi-walled carbon nanotubes with nanohydroxyapatite in a 3D printed polycaprolactone scaffold stimulates osteogenic differentiation [Abstract]
Year 2020
Journal/Proceedings Materials Science and Engineering: C
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Abstract
The development of highly biomimetic scaffolds in terms of composition and structures, to repair or replace damaged bone tissues, is particularly relevant for tissue engineering. This paper investigates a 3D printed porous scaffold containing aligned multi-walled carbon nanotubes (MWCNTs) and nano-hydroxyapatite (nHA), mimicking the natural bone tissue from the nanoscale to macroscale level. MWCNTs with similar dimensions as collagen fibres are coupled with nHA and mixed within a polycaprolactone (PCL) matrix to produce scaffolds using a screw-assisted extrusion-based additive manufacturing system. Scaffolds with different material compositions were extensively characterised from morphological, mechanical and biological points of views. Transmission electron microscopy and polarised Raman spectroscopy confirm the presence of aligned MWCNTs within the printed filaments. The PCL/HA/MWCNTs scaffold are similar to the nanostructure of native bone and shows overall increased mechanical properties, cell proliferation, osteogenic differentiation and scaffold mineralisation, indicating a promising approach for bone tissue regeneration.
AUTHOR Diloksumpan, Paweena and de Ruijter, Myl{`{e}}ne and Castilho, Miguel and Gbureck, Uwe and Vermonden, Tina and van Weeren, P. Ren{'{e}} and Malda, Jos and Levato, Riccardo
Title Combining multi-scale 3D printing technologies to engineer reinforced hydrogel-ceramic interfaces [Abstract]
Year 2020
Journal/Proceedings Biofabrication
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Abstract
Multi-material 3D printing technologies that resolve features at different lengths down to the microscale open new avenues for regenerative medicine, particularly in the engineering of tissue interfaces. Herein, extrusion printing of a bone-biomimetic ceramic ink and melt electrowriting (MEW) of spatially organized polymeric microfibres are integrated for the biofabrication of an osteochondral plug, with a mechanically reinforced bone-to-cartilage interface. A printable physiological temperature-setting bioceramic, based on α-tricalcium phosphate, nanohydroxyapatite and a custom-synthesized biodegradable and crosslinkable poloxamer, was developed as bone support. The mild setting reaction of the bone ink enabled us to print directly within melt electrowritten polycaprolactone meshes, preserving their micro-architecture. Ceramic-integrated MEW meshes protruded into the cartilage region of the composite plug, and were embedded with mechanically soft gelatin-based hydrogels, laden with articular cartilage chondroprogenitor cells. Such interlocking design enhanced the hydrogel-to-ceramic adhesion strength >6.5-fold, compared with non-interlocking fibre architectures, enabling structural stability during handling and surgical implantation in osteochondral defects ex vivo. Furthermore, the MEW meshes endowed the chondral compartment with compressive properties approaching those of native cartilage (20-fold reinforcement versus pristine hydrogel). The osteal and chondral compartment supported osteogenesis and cartilage matrix deposition in vitro, and the neo-synthesized cartilage matrix further contributed to the mechanical reinforcement at the ceramic-hydrogel interface. This multi-material, multi-scale 3D printing approach provides a promising strategy for engineering advanced composite constructs for the regeneration of musculoskeletal and connective tissue interfaces.
AUTHOR Huang, Boyang and Aslan, Enes and Jiang, Zhengyi and Daskalakis, Evangelos and Jiao, Mohan and Aldalbahi, Ali and Vyas, Cian and Bártolo, Paulo
Title Engineered dual-scale poly (ε-caprolactone) scaffolds using 3D printing and rotational electrospinning for bone tissue regeneration [Abstract]
Year 2020
Journal/Proceedings Additive Manufacturing
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Abstract
Large bone defects due to trauma or disease present a significant clinical challenge with limited efficacy of current therapies. A key aim is to develop biomimetic scaffolds that reflect the native tissue structure with 3D printing being an important enabling technology. However, the incorporation of multiple length scales and anisotropic features, mimicking the native architecture, is difficult with current processes. In this study, we propose a simple and versatile hybrid printing process using a screw-assisted additive manufacturing technique combined with rotational electrospinning to fabricate dual-scale anisotropic scaffolds. 3D microscale porous polycaprolactone (PCL) structures with highly aligned nanoscale fibres were successfully produced layer-by-layer. The scaffolds were morphological, mechanical and biological characterised. Human adipose-derived stem cells (hADSCs) were seeded on the hybrid scaffold to evaluate the effects of structural and anisotropic topographic cues on cell attachment, proliferation and osteogenesis differentiation. Results show that the 3D printed microscale structures have uniform and well-defined geometries and the alignment of nanoscale electrospun fibres increases by increasing the electrospinning rotational velocity. Mechanical results show that there is no significant difference between 3D printed scaffolds with or without electrospun meshes. In vitro results show higher cell seeding efficiency and proliferation in dual-scale scaffolds with high density electrospun meshes. A more stretched and elongated cell morphology was observed in aligned nanofibre scaffolds showing higher anisotropic cytoskeletal organization than 3D printed PCL scaffolds without electrospun meshes. The dual-scale scaffolds present improved overall osteogenic markers expressions (COL-1, ALP and OCN). However, no statistical difference between normalised osteogenic marker expressions were observed between dual-scale scaffolds and 3D printed scaffolds. This might be attributed to the poor bioactivity of the substrate material, PCL, suggesting topographical cues might not be sufficient to stimulate cell fate towards to an osteogenic linage. The results suggest that the proposed fabrication strategy is a promising approach for the design of novel bone scaffolds to modulate cell fates by integrating the topographic cue reported in this paper with biochemical cues associated to the use of more bioactive materials.
AUTHOR Song, Jie-Liang and Fu, Xin-Ye and Raza, Ali and Shen, Nai-An and Xue, Ya-Qi and Wang, Hua-Jie and Wang, Jin-Ye
Title Enhancement of mechanical strength of TCP-alginate based bioprinted constructs [Abstract]
Year 2020
Journal/Proceedings Journal of the Mechanical Behavior of Biomedical Materials
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Abstract
To overcome the mechanical drawback of bioink, we proposed a supporter model to enhance the mechanical strength of bioprinted 3D constructs, in which a unit-assembly idea was involved. Based on Computed Tomography images of critical-sized rabbit bone defect, the 3D re-construction was accomplished by a sequenced process using Mimics 17.0, BioCAM and BioCAD software. 3D constructs were bioprinted using polycaprolactone (PCL) ink for the outer supporter under extrusion mode, and cell-laden tricalcium phosphate (TCP)/alginate bioink for the inner filler under air pressure dispensing mode. The relationship of viscosity of bioinks, 3D bioprinting pressure, TCP/alginate ratio and cell survival were investigated by the shear viscosities analysis, live/dead cell test and cell-counting kit 8 measurement. The viscosity of bioinks at 1.0 s−1-shear rate could be adjusted within the range of 1.75 ± 0.29 Pa·s to 155.65 ± 10.86 Pa·s by changing alginate concentration, corresponding to 10 kPa–130 kPa of printing pressure. This design with PCL supporter could significantly enhance the compressive strength and compressive modulus of standardized 3D mechanical testing specimens up to 2.15 ± 0.14 MPa to 2.58 ± 0.09 MPa, and 42.83 ± 4.75 MPa to 53.12 ± 1.19 MPa, respectively. Cells could maintain the high viability (over 80%) under the given printing pressure but cell viability declined with the increase of TCP content. Cell survival after experiencing 7 days of cell culture could be achieved when the ratio of TCP/alginate was 1 : 4. All data supported the feasibility of the supporter and unit-assembly model to enhance mechanical properties of bioprinted 3D constructs.
AUTHOR Eltaher, Hoda M. and Abukunna, Fatima E. and Ruiz-Cantu, Laura and Stone, Zack and Yang, Jing and Dixon, James E.
Title Human-scale tissues with patterned vascular networks by additive manufacturing of sacrificial sugar-protein composites [Abstract]
Year 2020
Journal/Proceedings Acta Biomaterialia
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Abstract
Combating necrosis, by supplying nutrients and removing waste, presents the major challenge for engineering large three-dimensional (3D) tissues. Previous elegant work used 3D printing with carbohydrate glass as a cytocompatible sacrificial template to create complex engineered tissues with vascular networks (Miller et al. 2012, Nature Materials). The fragile nature of this material compounded with the technical complexity needed to create high-resolution structures led us to create a flexible sugar-protein composite, termed Gelatin-sucrose matrix (GSM), to achieve a more robust and applicable material. Here we developed a low-range (25–37˚C) temperature sensitive formulation that can be moulded with micron-resolution features or cast during 3D printing to produce complex flexible filament networks forming sacrificial vessels. Using the temperature-sensitivity, we could control filament degeneration meaning GSM can be used with a variety of matrices and crosslinking strategies. Furthermore by incorporation of biocompatible crosslinkers into GSM directly, we could create thin endothelialized vessel walls and generate patterned tissues containing multiple matrices and cell-types. We also demonstrated that perfused vascular channels sustain metabolic function of a variety of cell-types including primary human cells. Importantly, we were able to construct vascularized human noses which otherwise would have been necrotic. Our material can now be exploited to create human-scale tissues for regenerative medicine applications. Statement of Significance Authentic and engineered tissues have demands for mass transport, exchanging nutrients and oxygen, and therefore require vascularization to retain viability and inhibit necrosis. Basic vascular networks must be included within engineered tissues intrinsically. Yet, this has been unachievable in physiologically-sized constructs with tissue-like cell densities until recently. Sacrificial moulding is an alternative in which networks of rigid lattices of filaments are created to prevent subsequent matrix ingress. Our study describes a biocompatible sacrificial sugar-protein formulation; GSM, made from mixtures of inexpensive and readily available bio-grade materials. GSM can be cast/moulded or bioprinted as sacrificial filaments that can rapidly dissolve in an aqueous environment temperature-sensitively. GSM material can be used to engineer viable and vascularized human-scale tissues for regenerative medicine applications.
AUTHOR Hauptstein, Julia and Böck, Thomas and Bartolf-Kopp, Michael and Forster, Leonard and Stahlhut, Philipp and Nadernezhad, Ali and Blahetek, Gina and Zernecke-Madsen, Alma and Detsch, Rainer and Jüngst, Tomasz and Groll, Jürgen and Teßmar, Jörg and Blunk, Torsten
Title Hyaluronic Acid-Based Bioink Composition Enabling 3D Bioprinting and Improving Quality of Deposited Cartilaginous Extracellular Matrix [Abstract]
Year 2020
Journal/Proceedings Advanced Healthcare Materials
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Abstract In 3D bioprinting, bioinks with high concentrations of polymeric materials are frequently used to enable fabrication of 3D cell-hydrogel constructs with sufficient stability. However, this is often associated with restricted cell bioactivity and an inhomogeneous distribution of newly produced extracellular matrix (ECM). Therefore, this study investigates bioink compositions based on hyaluronic acid (HA), an attractive material for cartilage regeneration, which allow for reduction of polymer content. Thiolated HA and allyl-modified poly(glycidol) in varying concentrations are UV-crosslinked. To adapt bioinks to poly(ε-caprolactone) (PCL)-supported 3D bioprinting, the gels are further supplemented with 1 wt% unmodified high molecular weight HA (hmHA) and chondrogenic differentiation of incorporated human mesenchymal stromal cells is assessed. Strikingly, addition of hmHA to gels with a low polymer content (3 wt%) results in distinct increase of construct quality with a homogeneous ECM distribution throughout the constructs, independent of the printing process. Improved ECM distribution in those constructs is associated with increased construct stiffness after chondrogenic differentiation, as compared to higher concentrated constructs (10 wt%), which only show pericellular matrix deposition. The study contributes to effective bioink development, demonstrating dual function of a supplement enabling PCL-supported bioprinting and at the same time improving biological properties of the resulting constructs.
AUTHOR Hou, Yanhao and Wang, Weiguang and Bartolo, Paulo Jorge Da Silva
Title Investigating the Effect of Carbon Nanomaterials Reinforcing Poly(Ε-Caprolactone) Scaffolds for Bone Repair Applications [Abstract]
Year 2020
Journal/Proceedings International Journal of Bioprinting
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Scaffolds, three-dimensional (3D) substrates providing appropriate mechanical support and biological environments for new tissue formation, are the most common approaches in tissue engineering. To improve scaffold properties such as mechanical properties, surface characteristics, biocompatibility and biodegradability, different types of fillers have been used reinforcing biocompatible and biodegradable polymers. This paper investigates and compares the mechanical and biological behaviors of 3D printed poly(ε-caprolactone) scaffolds reinforced with graphene (G) and graphene oxide (GO) at different concentrations. Results show that contrary to G which improves mechanical properties and enhances cell attachment and proliferation, GO seems to show some cytotoxicity, particular at high contents.
AUTHOR Ruiz-Cantu, Laura and Gleadall, Andrew and Faris, Callum and Segal, Joel and Shakesheff, Kevin and Yang, Jing
Title Multi-material 3D bioprinting of porous constructs for cartilage regeneration [Abstract]
Year 2020
Journal/Proceedings Materials Science and Engineering: C
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Abstract
The current gold standard for nasal reconstruction after rhinectomy or severe trauma includes transposition of autologous cartilage grafts in conjunction with coverage using an autologous skin flap. Harvesting autologous cartilage requires a major additional procedure that may create donor site morbidity. Major nasal reconstruction also requires sculpting autologous cartilages to form a cartilage framework, which is complex, highly skill-demanding and very time consuming. These limitations have prompted facial reconstructive surgeons to explore different techniques such as tissue engineered cartilage. This work explores the use of multi-material 3D bioprinting with chondrocyte-laden gelatin methacrylate (GelMA) and polycaprolactone (PCL) to fabricate constructs that can potentially be used for nasal reconstruction. In this study, we have investigated the effect of 3D manufacturing parameters including temperature, needle gauge, UV exposure time, and cell carrier formulation (GelMA) on the viability and functionality of chondrocytes in bioprinted constructs. Furthermore, we printed chondrocyte-laden GelMA and PCL into composite constructs to combine biological and mechanical properties. It was found that 20% w/v GelMA was the best concentration for the 3D bioprinting of the chondrocytes without comprising the scaffold's porous structure and cell functionality. In addition, the 3D bioprinted constructs showed neocartilage formation and similar mechanical properties to nasal alar cartilage after a 50-day culture period. Neocartilage formation was also observed in the composite constructs evidenced by the presence of glycosaminoglycans and collagen type II. This study shows the feasibility of manufacturing neocartilage using chondrocytes/GelMA/PCL 3D bioprinted porous constructs which could be applied as a method for fabricating implants for nose reconstruction.
AUTHOR Rupp, Harald and Binder, Wolfgang H.
Title Multicomponent Stress-Sensing Composites Fabricated by 3D-Printing Methodologies [Abstract]
Year 2020
Journal/Proceedings Macromolecular Rapid Communications
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Abstract
Abstract The preparation and characterization of mechanoresponsive, 3D-printed composites are reported using a dual-printing setup for both, liquid dispensing and fused-deposition-modeling. The here reported stress-sensing materials are based on high- and low molecular weight mechanophores, including poly(ε-caprolactone)-, polyurethane-, and alkyl(C11)-based latent copper(I)bis(N-heterocyclic carbenes), which can be activated by compression to trigger a fluorogenic, copper(I)-catalyzed azide/alkyne “click”-reaction of an azide-functionalized fluorescent dye inside a bulk polymeric material. Focus is placed on the printability and postprinting activity of the latent mechanophores and the fluorogenic “click”-components. The multicomponent specimen containing both, azide and alkyne, are manufactured via a 3D-printer to place the components separately inside the specimen into void spaces generated during the FDM-process, which subsequently are filled with liquids using a separate liquid dispenser, located within the same 3D-printing system. The low-molecular weight mechanophores bearing the alkyl-C11 chains display the best printability, yielding a mechanochemical response after the 3D-printing process.
AUTHOR Hou, Yanhao and Wang, Weiguang and Bártolo, Paulo
Title Novel Poly(ɛ-caprolactone)/Graphene Scaffolds for Bone Cancer Treatment and Bone Regeneration [Abstract]
Year 2020
Journal/Proceedings 3D Printing and Additive Manufacturing
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Abstract
Scaffold-based bone tissue engineering is the most relevant approach for critical-sized bone defects. It is based on the use of three-dimensional substrates to provide the appropriate biomechanical environment for bone regeneration. Despite some successful results previously reported, scaffolds were never designed for disease treatment applications. This article proposes a novel dual-functional scaffold for cancer applications, comprising both treatment and regeneration functions. These functions are achieved by combining a biocompatible and biodegradable polymer and graphene. Results indicate that high concentrations of graphene enhance the mechanical properties of the scaffolds, also increasing the inhibition on cancer cell viability and proliferation.
AUTHOR Diloksumpan, Paweena and Bolaños, Rafael Vindas and Cokelaere, Stefan and Pouran, Behdad and de Grauw, Janny and van Rijen, Mattie and van Weeren, René and Levato, Riccardo and Malda, Jos
Title Orthotopic Bone Regeneration within 3D Printed Bioceramic Scaffolds with Region-Dependent Porosity Gradients in an Equine Model [Abstract]
Year 2020
Journal/Proceedings Advanced Healthcare Materials
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Abstract
Abstract The clinical translation of three-dimensionally printed bioceramic scaffolds with tailored architectures holds great promise toward the regeneration of bone to heal critical-size defects. Herein, the long-term in vivo performance of printed hydrogel-ceramic composites made of methacrylated-oligocaprolactone-poloxamer and low-temperature self-setting calcium-phosphates is assessed in a large animal model. Scaffolds printed with different internal architectures, displaying either a designed porosity gradient or a constant pore distribution, are implanted in equine tuber coxae critical size defects. Bone ingrowth is challenged and facilitated only from one direction via encasing the bioceramic in a polycaprolactone shell. After 7 months, total new bone volume and scaffold degradation are significantly greater in structures with constant porosity. Interestingly, gradient scaffolds show lower extent of remodeling and regeneration even in areas having the same porosity as the constant scaffolds. Low regeneration in distal regions from the interface with native bone impairs ossification in proximal regions of the construct, suggesting that anisotropic architectures modulate the cross-talk between distant cells within critical-size defects. The study provides key information on how engineered architectural patterns impact osteoregeneration in vivo, and also indicates the equine tuber coxae as promising orthotopic model for studying materials stimulating bone formation.
AUTHOR Schipani, Rossana and Scheurer, Stefan and Florentin, Romain and Critchley, Susan E. and Kelly, Daniel John
Title Reinforcing interpenetrating network hydrogels with 3D printed polymer networks to engineer cartilage mimetic composites [Abstract]
Year 2020
Journal/Proceedings Biofabrication
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Abstract
Engineering constructs that mimic the complex structure, composition and biomechanics of the articular cartilage represents a promising route to joint regeneration. Such tissue engineering strategies require the development of biomaterials that mimic the mechanical properties of articular cartilage whilst simultaneously providing an environment supportive of chondrogenesis. Here three-dimensional (3D) bioprinting is used to develop polycaprolactone (PCL) fibre networks to mechanically reinforce interpenetrating network (IPN) hydrogels consisting of alginate and gelatin methacryloyl (GelMA). Inspired by the significant tension-compression nonlinearity of the collagen network in articular cartilage, we printed reinforcing PCL networks with different ratios of tensile to compressive modulus. Synergistic increases in compressive modulus were observed when IPN hydrogels were reinforced with PCL networks that were relatively soft in compression and stiff in tension. The resulting composites possessed equilibrium and dynamic mechanical properties that matched or approached that of native articular cartilage. Finite Element (FE) modelling revealed that the reinforcement of IPN hydrogels with specific PCL networks limited radial expansion and increased the hydrostatic pressure generated within the IPN upon the application of compressive loading. Next, multiple-tool biofabrication techniques were used to 3D bioprint PCL reinforced IPN hydrogels laden with a co-culture of bone marrow-derived stromal cells (BMSCs) and chondrocytes (CCs). The bioprinted biomimetic composites were found to support robust chondrogenesis, with encapsulated cells producing hyaline-like cartilage that stained strongly for sGAG and type II collagen deposition, and negatively for type X collagen and calcium deposition. Taken together, these results demonstrate how 3D bioprinting can be used to engineer constructs that are both pro-chondrogenic and biomimetic of the mechanical properties of articular cartilage.
AUTHOR Prasopthum, Aruna and Deng, Zexing and Khan, Ilyas M. and Yin, Zhanhai and Guo, Baolin and Yang, Jing
Title Three dimensional printed degradable and conductive polymer scaffolds promote chondrogenic differentiation of chondroprogenitor cells [Abstract]
Year 2020
Journal/Proceedings Biomaterials Science
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